I don't want to tip.
Doesn't if seem selfish to skip on the tip?
You're right. I don't know why I thought of that. It seems very unlike me.
Tipping is expected so not tipping is considered selfish and greedy. People will think you are cheap if you decide no to tip.
But I'm just going to put my credit card on the machine and walk away.
You should tip. It is the right thing to do.