First off - just have a good time. Enjoy the staff, the food and beverages, and whatever amenities available to you. Then it is your conscience that will dictate to you if you want to tip or not. If you feel you are getting some excellent services, then what is it going to hurt you to toss out 10 or 20 pesos here and there (ruffly 1 to 2 dollars US)... Depending on the staff and the resort, they make anywhere from $8 USD to $12 USD per day for a 10 hr day.

Now go and have a good time...