For a variety of reasons, the thrift shop where I volunteer allows us to "check out" items without paying for them. I draw a line down the middle of my card, front and back, and use it often. When the card gets filled, I clear it all at once. And then I round up. Today I had the manager ring me out, and then I added ~$45 so the total was a nice, round number. I appreciate that this system exists, and I'm happy to add a little extra to the cause.
I also thought of this thread when I was at Costco this week. Of course, I returned my cart and then straightened up the ones in front of it. Your inspiration is greatly appreciated. Hmmm, allow me to elaborate on this, if you will. I have always done stuff like this, but never thought of it as a good deed. I just thought I was a slightly OCD* weirdo. Thanks for helping me re-frame some ingrained behavior.
*My friend says it's actually "CDO" because the letters MUST be in alphabetical order. Makes sense to me.