Step up to the register with a coupon for a can of Alpo dog food at Shop 'n Save and you'll pay less sales tax on your pooch's dinner than if you bought the same can at the same price at two of the supermarket chain's biggest competitors, Giant Eagle and Wal-Mart.

		Getting a refund Customers who are charged the higher sales tax rate can request a refund from the revenue department by filing an appeal online at www.revenue.state.pa.us or by completing paper form Rev-65, which can be downloaded from the site.

How can that be? It comes down to when the sales tax is applied.

The state tax code says consumers should have to pay tax based only on an item's price after any coupons are deducted. But some stores calculate sales tax on the full, before-coupon price, meaning their customers shell out more tax. Such stores say their registers can't handle the extra documentation the state Revenue Department requires to extend the tax break.

Earlier this year, after the Post-Gazette reviewed the coupon sales tax practices at several chains, Shop 'n Save made good on a promise to fix its registers so that they calculate sales tax based on the discounted, after-coupon price.

Wal-Mart also said in March that it planned to reset its registers statewide so that customers with coupons would be charged the lower rate. The change required upgrades to the stores' computers, but the fixes didn't pass muster with the state, spokesman Marty Heires said. Wal-Mart is still working on a solution, he said.

The state, which levies a 6 percent sales tax and collects Allegheny County's 1 percent sales tax, requires detailed information so that auditors know for sure that coupons customers are using are for taxable items.

The way retailers handle coupons and sales tax is not an issue with many items, since most food, clothing and medicines are exempt from Pennsylvania sales tax. But hundreds of other everyday products, including soft drinks, cosmetics, soaps, detergents, shampoo, paper goods and pet food, are taxable.

Giant Eagle, the region's largest grocer, began researching upgrades for its registers in March in response to the PG article that questioned some area retailers' sales tax policies, spokesman Rob Borella said.

The O'Hara-based chain believes it has found a fix that would meet the state's record-keeping requirements and allow it to begin charging customers less tax. But Borella said the chain wasn't sure how soon any changes might be made.

State revenue department spokesman Steve Kniley has said merchants who charged more tax were not violating the law. But he said stores that chose to extend the tax break were "doing right by their customers."

Consumers who don't like a particular store's policy should complain, Kniley said.