Missing Dollar Puzzle

Solve the Missing Dollar Puzzle

Three guests check into a hotel. The manager says the bill is 300 dollars, so each of the guests pays 100 dollars, takes their key, and leaves. Later that night the manager realizes that he should have charged them 250 dollars instead of 300 dollars. He calls a bell boy and gives him 50 dollars, to return to the guests. On his way up, the bellboy realizes there is no way for him to equally distribute the 50 dollars in 3 parts. Since he was a bit dishonest himself, he decides to keep 20 dollars for himself and gives back the guests 10 dollars each. As the guests got 10 dollars back, each guest had paid 90 dollars, bringing the total to 270 dollars and the bellboy had kept 20 dollars for himself. Adding the amount it totals 290 dollars, then what happened to the remaining 10 dollars?