The missing dollar

Three men decided to split the cost of a hotel room. The hotel manager gave them a price of 30$..

The men split the bill evenly, each paying $10, and went to their room. However, 

the hotel manager realized that it was a Wednesday night, which meant the 

hotel had a special: rooms were only $25. He had overcharged them $5

He called the bellboy, gave him five one-dollar bills and told him to return it to the men.

When the bellboy explained the situation to the men, they were so pleased at the honesty 

of the establishment that they promptly tipped the bellboy $2 of the $5 he had returned and

each kept $1 for himself.

So each of the three men ended up paying $9 (their original $10, minus $1 back)

totalling $27, plus $2 for the bellboy makes 29$...

Where did the extra dollar go?