Technically, no. Here in FLorida at least, the law says you cannot add a surcharge for payment by credit card. It does, however, permit a discount for cash.

I recall that at least one of my historical credit card merchant account agreements stated it the same way.

Once, a few years ago, a disgruntled customer was not happy with our cash discount and not getting it when paying by card. She thought it amounted to a card surcharge and surreptitiously had a credit card customer service agent on the line when she called to complain. Halfway through the agent interrupted and asked me point blank to read our terms & conditions, understood our position, and informed the complaining lady that we were not violating anything.