As for counters and drive-up windows, I generally don't tip at them at all. I'm not getting any more service from them than a grocery checker, ...
Fern
This reminded me of when I visited my son at Twenty-nine Palms. We went to the supermarket on base. There was a tip jar there for the baggers. Apparently, they worked for tips only--no wage at all. I've never seen that anywhere else.