My advice is to instantly make a bid in a new round. Why wait until the last second? It seems like most try to do that, I don't understand why? It goes against all logic in negotiations. Make your presence known, don't try to piss off the other bidders and so forth.

I usually bid first for at least 10 rounds, then I might try to sneak in a late bid hoping that the other guy thinks that I have given up. But not before that.