The Dodd-Frank act, 2010, with the Durbin Amendment, made it so that vendors could impose a restriction on credit card purchases up to 10 dollars. http://en.wikipedia.org/wiki/Dodd%E2%80%93Frank_Wall_Street_...

Citation please. I've been charged extra at my favorite Chinese restaurant for using a card, so it's not that I don't believe you, but I would really like to know the relevant decision. (Upvoted)

Visa and Mastercard settled so there was no decision needed.

http://www.justice.gov/atr/public/press_releases/2010/262867...

I believe American Express settled later.