I own a couple of fast food franchises, and we recently were given the green light for the credit card tipping. We've always had the tip jar.
Funnily enough, many customers are glad we got it. They always wanted to tip, but never had the cash. On the other hand, the staff is trained that tips are obviously not mandatory nor expected, and the default instructions for credit card payers is "Oh, just hit the bottom button" (None, no tip).
Our compensation structure remains the same, regardless of tips. Tips, to me, are evidence of exceeding expectations, service-wise. So, every week, I double the tips earned for the top three employees on a tips-per-hour basis. Talk about incentive...it's really upped our service game!
Personally, I don't go out to eat. Especially not fast food. But if I received incredible service at a customarily non-tipped place, I would tip. You shouldn't feel guilty about not tipping either. From my experience, it's not expected - just a pleasant surprise.