Watch your wallet—you could have to pay more to use your Visa or Mastercard. As the result of a class action settlement last July, merchants now have the option of tacking on a surcharge as high as 4%. Visa and Mastercard had always prohibited the charge, but agreed to change the rules as part of the settlement of an antitrust suit brought by retailers. The surcharge is supposed to equal the actual cost of processing the credit card transaction, which is typically 1.5% to 3%. Under the agreement, that fee is capped at 4%.

While many gas stations have been charging more to use credit cards for years, some retail experts don’t expect other merchants to follow suit. The National Retail Federation polled its members and found that none planned to add the fee. Toys-R-Us and Target told NBC News they would not pass the buck to their shoppers.