The Story of Dollar That Wasn't Lost

How it was lost? 

All you need to think on the behalf of travelers to simplify things around.

Initially they spent $30 for the stay. Now these $30 distributed into 2 parts viz. 25 & 5 by clerk.  Out of 5, travelers received only 3 that means now they have spent $27 only. Out of 27, clerk had 25 & bellboy took 2! Trying to add bellboy's 2 in 27 is pointless but the base of this quiz!