A Poker Tracker Big Bet (i.e. what is being measured) is 2 x big blind (this is a convention taken from limit poker, which Poker Tracker was created to work with).

So, at the 5c/10c tables, one BB (often called PTBB on this board to avoid confusion) is 20c - you are winning $2.40 per 100 hands.

And yes, it is a very respectable winrate - you should be happy with that, and you'll soon be rolled for 10c/25c (when your BR reaches $500). Nice going.