From gopher + rounding.
When someone goes on a food run and "rounds up" the price of your food, thus failing to give you change. Often "unintentional."
If you give someone $10 to go pick you up a Big Mac and you never get change, they've done some grounding.
"Hey, did you ever get your change from Mike after that Taco Bell run?"
"No, that son of a bitch does some serious grounding."