VIRGINIA BEACH – With the struggling economy, a lot of people are pinching pennies these days. But how closely do you watch prices at the grocery store?

Do you check store receipts to make sure the sales tax you paid was charged correctly?

13News Investigators found out that’s not always the case.

Items like medicated powder, mouthwash, eye drops and acne products are supposed to be tax free by state law.

But 13News Investigators found some of the area's largest grocery stores and retailers getting it wrong.

Carol Miller of Virginia Beach likes a bargain and will drive to a number of different stores to get a good price.

"I never really looked at anything from a tax perspective because you just trust that they’re doing what they’re supposed to be doing," she admits.

13News investigators bought a number of over-the-counter-pharmacy items at Kroger stores. In most cases, Kroger got it right. But we were charged 5-percent sales tax on medicated mouthwash at the store in Hilltop and on eye drops we bought at Kroger at Wards Corner. Both products, the state says, are tax free.

According to the Virginia Tax Code, "nonprescription drugs and proprietary drugs" are exempt from taxes if they are used in "the cure, mitigation, treatment, or prevention of disease in human beings."

Powders (medicated), first aid healing agents, cleaners, itch, rash relievers) medicated powders, first aid products like Neosporin and itch and rash relievers also are tax free.

But we were charged sales tax on each of those items at the Target in Hilltop as we randomly bought products on the states list of tax-exempt items.

Video: Stores charging tax they shouldn't

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In an email response, Target executives told us, “We have made our teams aware of the issue so we can take appropriate action. Thank you for bringing this to our attention.”

Joel Davison with Virginia Department of Taxation told 13-News,

"We leave it to the retailers to in large part police themselves."

Davison says with just 200 state auditors and more than 200,000 retailers, it's impossible to do more than random checks of stores and their receipts.

The Department of Taxation told 13News it expects more issues with smaller mom and pop stores and has higher expectations for large corporations with sophisticated computer systems. Because these stores deal with a larger volume, a mistake would greatly magnify the amount of tax collected that customers shouldn’t have paid.

"The issues are not as prevalent with the larger retailers because of their corporate umbrella. They have people looking over these lists. They want to get it right," stresses Davison.

Food Lion executives told by us by phone the cash registers at all 327 stores in Virginia are centrally programmed. And they conduct review of taxable products on a regular basis.

At the Food Lion in Hilltop, among the items we bought, we paid sales tax on Noxzema Medicated Shave Cream, witch hazel, eye drops and medicated powder -- all products the state says are tax free.

“Computers are not infallible and neither are the people who put the information into the computers," shopper Pat Lowery noted.

When pennies on a dollar add up to millions in taxes that shouldn't have been collected is hard to tell. We were overcharged by about $3.00 on items

consumers might buy on a fairly regular basis. And the state admits it does not have the people to do what we did.

"People like yourself bring this to our attention. I mean, these are stores we're going to check out," Davison notes.

So, what do you do if you want your money back? The state says you need to go back to the store with your receipt for a refund. We'll tell you what the stores had to say about overcharging us. Watch tonight on 13News at 11.