I don't think they're all that common (yet) for day to day purchases, at least where I live. If anything, there are more businesses that have minimum purchase amounts and/or surcharge for card use than ones that don't accept cash at all. I suspect that the US won't be close to completely cashless unless swipe fees go way down--and lowering those fees would be problematic for consumers as well.

Speaking of cashless, I don't think I've ever seen anyone pay for a rental car or hotel room with cash. Is that still an option?