CLEVELAND -- Carole Fontaine thinks about it every time she sees the scale at the grocery store.

"I don't want to pay more than I have to pay," said Fontaine.

The Five On Your Side consumer investigation exposed how you can be cheated.

Fontaine said, "We just watch really well what we are spending and how much stuff is supposed to be, should be, when we check out."

Fontaine and her daughter weigh everything before they check out.

"It will give you a good idea of how much you actually purchased," said Mike Nix, an inspector with the Summit County Auditor's Office.

Nix and his coworkers visit every store in Summit County every three or four months.

One by one, they check each scale for accuracy.

"Anything that's weighed or measured we do," Nix said.

The inspectors said they rarely see a grocery scale fail, and the Twinsburg Giant Eagle NewsChannel5 visit has a great record. The problems come from operator error.

Nix said, "You want to make sure you are paying for the product not the container."

When you buy food sold by weight, you're legally only supposed to pay for the weight of the food, not what's holding it.

NewsChannel5 decided to do some shopping of their own. With a hidden camera rolling, the On Your Side consumer team visited five grocery store chains.

NewsChannel5 purchased 32 items sold by weight -- everything from seafood to salad. They then weighed all their purchases on a scale borrowed from the auditor's office.

The consumer team found they were overcharged for 10 items.

Their biggest discrepancy came from a Cleveland Walmart SuperCenter.

They paid more than $10 for what was supposed to be 4.37 pounds of chicken breasts. The chicken with packaging weighed in at 4.45 pounds.

When they we dumped out the chicken, the packaging alone weighed close to half a pound and NewsChannel5 discovered they had paid for 85 cents worth of packaging.

And when Walmart weighed a chicken salad sandwich, they didn't account for the packaging at all. That cost NewsChannel5 another 8 cents.

The same was true with a stuffed mushroom at Heinen's.

The label weight was just above a half-pound. That's the same weight they got when it was in the packaging, meaning NewsChannel5 overpaid by 19 cents.

Crab legs are something you should watch out for because they're so expensive.

NewsChannel5 purchased $14 worth of crab legs at a Giant Eagle. They didn't know they were paying 41 cents for the weight of the Styrofoam tray.

Although there's not much you can do at checkout when you buy prepackaged items, there's a lot you can do when it comes to your produce that's weighed at the register.

"Look for a zero," said Dale Minninger, a Summit County Inspector

Make sure nothing is obstructing the scale when your food is being weighed.

Undercover cameras were rolling as a Walmart checker leaned over to weigh produce. Her long name tag fell on the scale almost every time.

Although it did not affect NewsChannel5's purchase that trip, it did affect consumer reporter Joy Benedict's receipt from weeks ago.

Benedict's three nectarines weighed in at more than 4 pounds, and her three plums weighed 2.8 pounds.

"If you don't think it's correct, ask for it to be re-weighed," Nix said.

Benedict did, and the receipt was corrected.

Fontaine said, "It's tough times. You want to get the best for your money."

That means being observant, knowing what you're buying, and not being afraid to call out a "shifty scale."

Additional Information:

More weight-to-price ratios actually turned out in favor of NewsChannel5 than against them. But, NewsChannel5 asked each company to comment on the discrepancies they did find.

Walmart did not respond, but you can read responses from Giant Eagle and Heinen's below.

Giant Eagle's response:

"Giant Eagle is committed to providing high quality foods at exceptional value to our customers. Giant Eagle works closely with officials from local weights and measures offices to ensure the accuracy of our scales and pricing systems, and we conduct our own daily equipment tests and inspections. Our Rocky River location passed a county inspection earlier this month with 100% accuracy. However, after learning of the pricing errors identified in the recent visit conducted by WEWS, we inspected all equipment again and found that the Seafood Department tare was not being calculated correctly. We immediately addressed the issue and re-trained all store team members.

When weighing product and determining total cost, Giant Eagle always removes the weight of the container -- also known as tare weight -- before pricing. Each of our products is assigned a set of specific containers, further helping us to keep tare weights constant and aiding in precise measurement. Giant Eagle is reaching out to the Ohio Department of Agriculture Weights and Measures office to ensure we are in compliance with all of their requirements and testing methods, and we are re-testing the scales at all of our Cleveland-area stores to ensure the highest degree of accuracy possible.
-Dan Donovan, Giant Eagle spokesperson."

Heinen's response:

"Heinen's strives to be perfect in our weighing and pricing practices and are very proud of our accuracy over the eighty years that we have been in business. Our commitment to accuracy has been validated through the random inspections conducted by The Division of Weights and Measures and we have been found to be within the acceptable guidelines virtually every inspection. We have reviewed our weighing and pricing processes to be sure our defined practices are understood and followed in the future. Heinen's is disappointed that Joy Benedict and the Channel 5 News team found a package incorrectly weighed during their trip to our store."