Road Trip Bathroom Break

When I am on a road trip and I need to tap a kidney (urinate), I usually pull off at a small town gas station. But for some reason I feel really guilty just making my deposit and leaving. I feel like I need to buy something from the station just in return for using their bathroom. I don't know why I feel this way? They offer their bathroom services free of charge, but you do get that "look", if you just walk in... and then walk out.... and I am not interested in pissing off a disgruntled, tired, underpaid gas station attendant who more than likely has a sawed off shotgun under the counter. So I usually try to find the cheapest thing I can, such as a piece of gum, purchase it and be on my way with a smile. I wonder if other people feel this way?