nl 50 value bet?

[breandan]

I limp on the button with black 7-7 after 3 limpers, we all have about 50$. No reads on anyone as this is my second orbit. The flop is 2c,4s,5c. Sb bets 50 cents into $3.00, one of the ep calls and I bump it to 3.50. (raise more here?) Sb folds and ep calls. Turn is Qh. Ep checks and i bet 8.00 into 10.00. Ep calls. River is 9d. I bet 12.00 for value. Standard or check behind turn or river? Thanks.