The "issue" is simply not *having* 4-5 dollars in cash. I always add my tip to the credit card receipt total.
Is it really about you? This is one of those utilitarian posts, where someone's just seeking practial information, but you seem to need to keep hitting how you never have cash on you, as if it were some accomplishment or point of honor. Fine. Someday you'll really need to have cash on you, and I'm sure your explanation of "simply not having 4-5 dollars in cash" will get you out of whatever the jam is. No one in this household is ever without his or her "emergency twenty," and that includes the eleven-year-old. I'm not literally asking for a response, but I do wonder how you pay for things like a coffee that's $1.25, or a bagel with cream cheese for $1.99. Because I might be that guy behind you in line (along with four or five others), thinking, Does that person really need to do a credit card transaction for something that small?