According to the most recently posted taxi rates it is about 500 pesos each way ( if you use USD, taxis only give a 10:1 conversion rate, so $50 USD each way). You can check with the concierge at Desire Pearl, I believe the current taxi rates are posted right beside the main lobby entrance
IMHO overall cheaper to just rent a car for a day while your at the resort, driving is easy and the highway is well marked, just obey the speed limits, etc