Gemini says that in USA it's legal except in Connecticut, Maine, Massachusetts, and Puerto Rico, but it's a gray are in other states and cite https://allaypay.com/blog/processing/credit-card-surcharge-l... that agree with that. Wikipedia agree https://en.wikipedia.org/wiki/Surcharge_(payment_systems)

My recommendation is ato ask a real layer instead of listening to randoms from the Internet that are not giving legal advice.

Here in Argentina it's nice that whatever price you see in the store window or shelf is the same number that you pay. (It's specially nice when you pay in cash). The only exception are the telephone companies, but they are consider shady anyway. (This is unlike USA that at the last second they add some random taxes and whatever, so you never know how much you are going to pay.)