Where'd the money go?

Three men walk into a restaurant for a set lunch. After their meal, they each hand over $10 to the waiter, which was the price of the meal. There were no additional charges or taxes. The owner was feeling rather generous that day and decided to charge the three men only $25, instead of the usual $30. So he instructed the waiter to return $5 to the men. The shrewd waiter thought it was inconvenient to split $5 equally among the three men, and decided to pocket $2 for himself. He duly gave $1 to each of them. Since the men eventually paid $27, and the waiter took $2, what happened to the missing dollar?
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This one still had me stumped momentarily three years on. Who can solve this?