The only penny auction sites I ever looked in to required you to buy something akin to "tokens" which equaled 1 penny in the auction basically. Each bid, even if you are not the final winner, you are still out the money, umm, excuse me, the "tokens".
Basically what it comes down to is a way to trick people in to thinking they are buying it cheaper then they really are. You may get lucky, but odds are you wont.
I havent even looked at any penny sites in a long time becuase of this. I doubt they have changed any, save for a new take on the old game.
Just my thoughts.