The Dishonest Bell Boy

Riddle: 3 FRIENDS GO INTO A HOTEL, BUT ONLY HAVE $30.00 FOR A ROOM. THEY TELL THE CLERK WE ARE REALLY TIRED AND WANT TO SHARE A ROOM, THEY ASK THE CLERK DO YOU HAVE ANYTHING FOR $30.OO, THE CLERK SAID WELL I HAVE ONE LEFT, SO THEY GET THE ROOM AND GO UP STAIRS TO THEIR ROOM, THE CLERK FEELS BAD NOW BECAUSE THE ROOM ONLY COST $25.00 SO HE TELLS THE BELL BOY TAKE THESE 5 -1 DOLLAR BILLS BACK TO THE 3 FRIENDS AND GIVE THEM THEIR MONEY BACK. BELL BOY PUTS 2 DOLLARS IN HIS POCKET AND GIVES THE FRIENDS 1 DOLLAR EACH. SO THEY REALLY PAID $9.00 EACH FOR THE ROOM IF BELL BOY KEPT THE REMAINING $2.00 WHAT HAPPENED TO THE EXTRA 1 DOLLAR?????