The missing dollar

Question: 3 travelling salesmen got a motel room for the night. The clerk said the room is $30. So they paid $10 each. Later, the clerk realized that the room is supposed to be only $25. The clerk gave $5 to the bellhop and told him to refund it to the 3 salesmen. The bellhop decided to keep $2 and he gave $1 to each of the 3 salesmen. That means each salesman paid $9. Ok, $9x3=$27 plus the $2 that the bellhop kept equals $29. Where did the other dollar go?