coolcat wrote:
Usually when I pay by credit card, I leave the restaurant's receipt copy
(signed with tip) at the table. I take my copy of the receipt and the check
with me. Is this wrong? Am I supposed to leave the check at the table? Does
it matter? Thanks.

Yes it is. Usually it shows the sales tax, but the credit card receipt does
not. Most places require by law a merchant to give you a receipt that shows the
tax.