On topic: Yes, per Visa and other card issuers and processors, a merchant can
set a minimum charge amount on credit, but not debit
, cards, with a $10 maximum limit.
refuse to shop there.
Another little gem: They are NOT allowed to "see your ID," as their only requirement from the processor is to check to see if the signature on the charge slip matches the signed card. They can
refuse to accept the transaction if the card is not signed, or has one of those cutesy "check ID" message written on the signature line. But if they ask you "may I see your ID," just say "no." If they refuse to accept a valid, signed card for a merchandise or service charge on a terminal-swiped card, they are violating their processing agreement, banking laws,
and probably even federal privacy laws. No one outside of Homeland Security or a commissioned law-enforcement officer gets to see your ID
... especially not a $8-an-hour clerk at some retail store...