I Hate Bookkeeping. Here's a riddle that explains why.

As a small business owner, bookkeeping occupies (IMO) way too much of my time.   This is time that I could be spending to make the hostel a better place.   I'm currently working with some programmers who are smarter than me to help with this situation.  However, when I explain to friends about my loathing of bookkeeping they don't seem to understand.  "It's easy math" they say.    Easy for some I say, but I have a mind that can get very easily confused with numbers.   

Take this riddle for example.   It's easy math, and I can actually explain it.   However, it's these kinds of little confusing math problems that confound and aggravate me when doing my bookkeeping.   Here you go.   Enjoy!

Three men are travelling and get tired, so they decide to spend the night at a nearby inn. When they go to the front desk, the innkeeper charges them $30, ($10 each), and the three men go into their rooms and go to sleep. Then the innkeeper realizes that he was only supposed to charge the men $25 total for the room, so he gives $5 to the bellboy to give to the men. But on the way to the men's rooms, the bellboy thinks to himself, "Hey, they can’t split $5 3 ways and I've been so good, I deserve some money." So he keeps $2 and gives the remaining $3 to the men. Because they each get $1 back, they paid $9 instead of $10 each. But 3 x $9 = $27 plus the $2 the bellboy = $29.  Where is the missing dollar?