HOUSTON -- Times are tight. We may watch our pennies and even clip coupons, but any savings we see can be wiped out with one overcharge at the register.

It's why investigative reporter Amy Davis is looking out for your bottom line.

You fight the crowds, get all the goods on your list, but at the end of a long grocery trip, you're sacked.

Who has the energy to keep an eagle eye on the register to make sure every item checks out as advertised?

"To be honest, I usually don't look at the prices when they're ringing it up," said shopper Orlando Moore. "I guess I should look at it."

"Actually, I should go over my receipt today, which I didn't do," admitted Kristin Tomei when she left the SuperTarget on Interstate 45 near Spring Cypress.

But if you're not watching out for you, who is?

The Texas Department of Agriculture Commissioner says he is committed to consumer protection.

We asked his office to show us which grocery stores had the worst record of overcharging customers at the checkout. It turns out the TDA had no idea.

The state used to spot check 1,200 retailers at random every year to make sure the prices you saw on the shelf matched the prices you'd get at checkout. But, for the last five years, those price checks have been left entirely to the consumer.

In 2003, Texas was faced with a major budget crisis and our legislature had to make a lot of cuts, explained Veronica Obregon, a spokeswoman for the TDA.

The routine price verification inspections were one of the first things to go. Instead, TDA now only inspects store scanners for accuracy if a consumer calls and complains about a specific store.

We asked the agency to check the scanners at the Kroger on Westpark and Buffalo Speedway to show us how it works.

Then we took the state's rules and conducted our own inspections at Randalls, Wal-Mart, H-E-B, Target and Kroger.

What did we find?

Every item checked out at H-E-B. Our receipt showed no errors.

We didn't get any overcharges at Randalls, either. We were actually undercharged by 65 cents.

It was the same story at Target when the cat food, priced at $8.49, rang up as $6.99.

Wal-Mart was the first store to overcharge us at the checkout.

Pears were marked $1 a pound, but our receipt shows we were charged a $1.44 a pound.

Wal-Mart undercharged us for Jif peanut butter, an error we noticed at multiple stores. The shelf says $3.18, but it rings up as $2.82.

The overcharges were highest at Kroger, where we were charged $3.89 for a frozen bag of edamame (soybeans) marked $2.59.

We were undercharged 50 cents for watermelon, but we still walked out paying too much.

And chances are if you're not checking, you might too.

"I won't walk out of the store and say, 'Oh well, it's only 30 cents,'" said Melanie Geisendorff.

And the Texas Department of Agriculture says you shouldn't.

"We want consumers to know that if they feel they are being overcharged for an item at a retail shop that they need to call and file a complaint," said Obregon.

You can file a complaint with the TDA by calling 1-800-TELL-TDA.

Filing a complaint will trigger an inspection. If inspectors find any items ringing up over the price listed in an ad or on the shelf, the store must stop selling the product until the price is corrected.

At the Kroger on Westpark, inspectors were charged $10.21 for pork chops instead of the sale price of $5.09 -- a $5 error that could make a big difference in your grocery budget.

"It's simple error and that's why we ask consumers to be aware," said Obregon.

If you're still not convinced you need to look over your receipts, you should know Kroger, H-E-B and Randalls all have a policy that if you are overcharged for an item, you can get one of that item for free. They don't usually offer it. You have to hold them to it.