VERY COMPLICATED

Riddle: Three guys go on a trip. They stop at a hotel. The clerk tells them it is $30.00 for a room, so they each pay $10.00. Later that day the hotel manager says, wait, its only $25.00 for a room, so he sends the clerk up to the guys' room to give them $5.00 back. One the way to the room, the clerk realizes he doesn't know how to split $5.00 among 3 people so he puts two dollars in his pocket. When he gets to the room he gives each man $1.00.

Well... 3x9=27+2=29 where did the other dollar go?

PLEASE TELL ME YOU CAN SOLVE THIS!!
GOOD LUCK!!!