Thrift store in Montgomery County – Discount and Sales Tax Question (Glenside: purchase, legal)

[The_Resourcer]

A church-affiliated thrift store in Glenside has a curious sales tax application, which when discovered and questioned by me, yielded no acceptable response by its workers.

On Mondays, this Glenside thrift store offers a 10% discount on one's purchase (as long as you first show your store member card).

One's receipt reveals this store applies two separate taxes on the purchase: one on the dollar amount discounted and one on the subtotal.

Example:
Let's say you purchase books from this store which total $10. You show your member's card and the store clerk applies the 10% discount on the $10 (-$1.00). The subtotal is now $9.00.

Montgomery County tax is 6%, which this thrift then applies to the $1.00 discount ($.06) AND the $9.00 subtotal ($.54), for a final total of $9.60!

No other Montgomery County retail store where I shop applies a double tax. In the same scenario as described above, the 6% tax would be applied only to the $9.00 subtotal for a final total of $9.54.

Is this legal for this thrift store to do? This thrift store is racking up that extra revenue, especially in cases where one purchases hundreds of dollars in taxable items from this store.

When questioned, the accountant and workers said, “It's just the way it is. That's how the registers are set up.”

Oh really? Maybe this store's registers need to be re-calibrated if this indeed not legal. Can any accountants out there address this issue? I'm just curious. Thanks!