My rule is rather anti-tip-tradition. I tip if the meal is above standard.

Most restaurants in ZA are below standard. So merely meeting standard means they still won't get a tip from me.

It's a vestige of traditional eating-out. But I don't feel bad for not tipping, I ain't their breadbasket and also I rather save my money up and help local homeless people (which I do do), than help some student studying. I gotta have my priorities straight, those students can get through it. Make or break.