Villain is 38/3/3 over about 50 hands. No post-flop reads at this point. How big do I make the river bet?

Party Poker - No Limit Holdem Ring game - Blinds: $0.25/$0.50 - 10 players
Converter

Stack sizes:
UTG: $52.65
UTG+1: $71.30
Hero: $53.15
MP1: $60.75
MP2: $27.22
MP3: $165.55
CO: $82.80
Button: $32.80
SB: $49
BB: $47.80

Pre-flop: (10 players) Hero is UTG+2 with T T
UTG calls, UTG+1 folds, Hero raises to $2.5, 5 folds, SB calls, 2 folds.

Flop: 7 2 J ($6, 2 players)
SB bets $1.5, Hero raises to $6, SB calls.

Turn: 4 ($18, 2 players)
SB checks, Hero checks.

River: T ($18, 2 players)
SB checks, Hero bets ???