You can read through 50+ pages of replies on this 'controversial' topic at trip advisor and other sites.
Here is a link to one.... https://www.tripadvisor.com/ShowTopic-g ... ublic.html
And this is a cut and paste from that link by a middle of the road type of reply...
3. Re: Tipping at all-inclusive resorts?
Oct 06, 2013, 10:32 AM
Completely a personal decision as mentioned. If it helps at all, the following seems to be "norm" and/or how we tipped - of course, everyone does as they are comfortable with, so certainly nothing is ever written in stone when it comes to this topic:
$1-2 -- Baggage handler at airport (should you choose to make use of their services to get your luggage and take you to your transfer - same on departure)
$5 -- transport driver (drop off and return - resort an hour from airport)
$2 -- porter at resort
$2-$3 -- buffet dining
$5 -- a la carte dining
$3-$5 -- daily for housekeeper
$2-$5 -- daily for fridge restocking (not always same person as housekeeper)
$1-$2 -- every second round of drinks (some people choose to tip a larger lump sum after being at bar/beach/pool for any given period of time in a day/evening - we went this route)
$5-$10 -- spa treatments
We also chose to tip:
-- the young man ($2 once) who carted the beach lounger cushions back and forth every day and evening.
-- the young man who climbed a tree outside our room to bring us two fresh coconuts one day ($1)
-- the older gentleman who tirelessly raked the beach twice a day ($2 twice)
-- taxi driver on shopping trip ($3 each way - short distance)
-- private excursion driver ($10 for both ways, about an hour trip each way)
-- crew on private excursion ($20)
Everyone is different - do whatever you are comfortable with and enjoy your trip! The Dominican people are some of the most hardworking, genuinely kind and friendly people I've ever met - a smile, "gracias" and going armed with a little Spanish is very appreciated, and a wonderful way to demonstrate respect and appreciation