All the above is true
As we do everywhere, guys over tipping has affected the expectations at most gringo oriented MP's - Tico's - native Costa Rican males - almost never tip; not part of their culuture - and girls, especially newer ones in the MP's, don't expect it. They also don't in tico MP's
If you want to give her $10, the world is not going to end, but it really depends on her, her attitude, and if she is a real PITA begging for tips - if she is licking your pin, and asks for a tip, its a shitty time to do so - IMO -
In places like the DelRey, the price you negociate is the price, although guys might negociate $60, with a $20 tip for good service - just do not pay in advance, negociate
what you want in advance, and if she changes the terms, or is a cunt or in anyway proves "better in the bar than in the cama <bed>" send her packing - some are famous for this, especially w/ newbi's - if she insists, you can, like Cuba Goding says "Show her the money" but it should not change hands until you are finished - also, she has to turn the cell phone off, and she is not there to watch cartoons
Also, consider joing CRT as a paid member - you will qualify for a number of discounts; well worth it, as well as support the board - also consider staying at a different place than the Hotel Del Rey - you are only charged the fee if you are staying there - not sure from reading your post if you realize that - its a bar and hotel, not a massage parlor or a whore house - there is also no fee to "take a girl out" of the place; all the girls are indies

Not like in Asia where "bar fines" are the norm.