the places where u use your card get charged a flat rate for every time a card is used and then on top of the charge they get charged a percentage of the transaction to. Many small businesses are starting to stop taking cards because of the increase in fees from the cc companies.
I would imagine that as long as they post it somewhere in the store then it's perfectly legal.
Yes, it's highly annoying. I actually just went to a dollar movie last night - same rules applied. (I know, I know..Going to a dollar movie you should carry cash..But it was a last minute thing) $2 for a movie - $5 minimum purchase... Yeah...
if it says it on the door or in side then the rules are rules and it is leagle but if it is not posted then you might have a chance to fight it but is it worth it you will spend more in lawyer fees
...use "cash" in the convenience store, then you'll eliminate the problem.....