My Vegas experience was cash only and some dude chasing me out of a CVS and trying to confiscate my license. When I talked to the manager the next day, he advised me their regional manager shut down purchases although their register allows them. Those of you who got through in Vegas must have had friendly cashiers. For the most part, you're going to get yelled at for trying - but I guess if you can just "get them to try" - it will work.