Three Guys in a Hotel

Three guys rent a hotel room for the night. When they get to the hotel they pay the $30 fee, then go up to their room. Soon the bellhop brings up their bags and gives the lawyers back $5 because the hotel was having a special discount that weekend. So the three lawyers decide to each keep one of the $5 dollars and to give the bellhop a $2 tip. However, when they sat down to tally up their expenses for the weekend the could not explain the following details:

Each one of them had originally paid $10 (towards the initial $30), then each got back $1 which meant that they each paid $9. Then they gave the bellhop a $2 tip. HOWEVER, 3 • $9 + $2 = $29

The guys couldn't figure out what happened to the other dollar. After all, the three paid out $30 but could only account for $29.

Can you determine what happened?

The math doesn't quite add up to me. They spent rather $27, that's $25 for the room and $2 for the tip. That's how come they got a total of $3 back.