This is a spot where I feel I'm losing a lot of value post flop because I don't know what to do. The CO here has $12 behind an $8 pot and checks to me, when I'm pretty sure I have the best hand at the moment. I'm also pretty sure I should cbet, but how much? Usually on this type of pot I'd put in around $5.5-7, but I'm not sure if it should be more (or less?) based on my opponents stack size.

Full Tilt No-Limit Hold'em, $0.25 BB (6 handed) - Full-Tilt Converter Tool from FlopTurnRiver.com

CO ($17.08)
Hero (Button) ($25)
SB ($31.79)
BB ($35.35)
UTG ($25)
MP ($43.76)

Preflop: Hero is Button with 10, 10
UTG bets $0.85, 1 fold, CO calls $0.85, Hero raises to $3.75, 3 folds, CO calls $2.90

Flop: ($8.70) 2, 2, 5 (2 players)
CO checks, Hero ?