The hotel's official position is that tipping is not necessary, but it is appreciated.
Cancun is certainly a tipping culture and many of us attending have means. That said, I would indeed encourage you to come prepared with some cash in order to tip when you receive good service.
You can tip in US dollars or Mexican pesos. One US dollar is approximately 20 pesos.
If you have the means, are inclined, and receive good service, here are a few lose guidelines that may help:
There is no need to tip at the percentages that have become normal in the US. It is hard to even try to do a percentage because you do not get a bill for meals or drinks.
Plan to leave $2-$3 per day for the maid who cleans your room.
If a bellman brings your bags to your room, consider tipping at least $1 per bag.
If you order drinks at a bar, it's probably not necessary to tip for each and every drink, but consider a couple dollars if you and a few others order several drinks. It's probably a good idea to tip more if you are ordering fancy mixed drinks.
At the self-serve buffets (breakfast and lunch), it is not necessary to tip, but if someone gave you extraordinary care, put a buck down.
At sit down restaurants for dinner (not buffets), plan on leaving between $2 to $5 dollars, more if you have a large party or if you receive great service.