It's not so much what the regulations require as what they allow. Previously, minimums weren't permitted by the CC companies. The regulations now allow, but don't require, merchants to set a minimum as long as it doesn't exceed $10.

CC companies have long prohibited credit card surcharges but permitted cash discounts. An essentially meaningless distinction as merchants just said "that's the discounted cash price, the undiscounted credit price is 3% higher".

So the bottom line is it really still varies by merchant.