yeah, you can play any number of rounds in an event and any games you and your opponent both made moves in will be rated.
I only played 2 rounds in a 3+2 blitz tourtament today and then withdrew, will it still be rated?

However, the rounds you did not play will count as a forfeit. In other words, the rounds you did not play will count as a loss. (Believe me, I know.)

No, only the round(s) where you made at least one move on both sides will be rated, so if u withdrew after 2 rounds, only the first 2 rounds will be rated. (Assuming we're talking about USCF Online Blitz Rating?)

However, the rounds you did not play will count as a forfeit. In other words, the rounds you did not play will count as a loss. (Believe me, I know.)
No, you just aren't paired if you leave.

If you are unlucky like me though, you would tap the withdraw button a second after you are paired because you were the last game
I only played 2 rounds in a 3+2 blitz tourtament today and then withdrew, will it still be rated?