My first trip to the DR

We are staying at an all inclusive. I went to an all inclusive in Cozumel for 3 nights and we didn't tip at all in the resort until check out. Then we left $50 in the room with a thank you note for the great service. My better traveled companion said that's how it's been done everywhere they've ever traveled.

But we've never been to DR. So can someone tell the tipping policies/expectations?