Depends. I try and hi-5 people when they look really upset so they know I'm more talented and a cooler/better person than them too
I'm kidding but I do prefer hi-5s instead of handshakes, aint nobody want other peoples sweaty hands all over you. Normally I'll accompany it with a good game.
Once I played someone who always beat me in a club competition, and after winning a close match where he was shouting COME ON and stuff I was about to shake his hand and just shouted COME ON and turned around and walked off
People watching laughed too.
EDIT: I should tell you the scorelines with this guy. I'd lost 6-1 6-1, 6-0 6-3, 7-6(3) 7-5 (he was injured and could barely run) and 6-2 6-0. I beat him 5-7 6-2 6-4 (it was 4-4 in the final set too).