Feels good when you make someone's day though, doesn't it?
When I last filled up my car I gave the petrol attendant R20 (which is definitely on the high side of what would be expected here - a couple of rand up to R5 would be the norm, I guess). He was immensely grateful and thanked me with a huge smile saying "This is my lunch!". As this was 7am I imagine that most days he probably has to accumulate several hours of tips before he gets lunch sorted. I felt ridiculously pleased with myself for some reason.