I have to agree with CF, it feels like you're trying too hard to be funny but it's just falling flat. It's not a bad idea, but I think you need to work on the execution.
Think of it this way - as a joke, the fact that you only take credit cards is the punchline, while panhandling is the setup. How often do you start a joke with the punchline? That's basically what you're doing here. It would probably be a lot more effective if you were just doing straightforward panhandling, but then when someone tries to give you money you hit them with "Oh, no, I'm sorry, we don't take cash". You let them react, then whip out the ipad and double down with "We do accept Visa, Mastercard, Amex, and most debit cards though." Get another reaction, then escalate with "and unfortunately we have to do a five dollar minimum, you know, fees and such". That's three punchlines, each time taking things to a slightly more absurd level, and each time providing an opportunity for more humor in the person's response.