“Credit cards may not work for sales tax or tips starting July 1.” By now, you’ve heard that claim, but whether it’s true depends on who you ask. The ads — funded by the Electronic Payments Coalition of banks, credit unions and card companies — argue that Illinois lawmakers must repeal the state’s first-in-the-nation Interchange Fee Prohibition Act, slated to take effect July 1. That law prohibits financial institutions from charging “swipe,” or interchange, fees on the tax and tip portions of