The Eastern Caribbean dollar (EC$) is used and US dollars are widely accepted. Unless rates are posted in US dollars, as is the norm with accommodations, it usually works out better to use EC dollars.
There aren’t many ATMs outside of Roseau and Portsmouth.
Some restaurant bills already include a 10% service charge, in which case additional tipping is optional. For exceptional service, a small extra amount will be much appreciated. If service is not included, tip 10% to 15%. Housekeeping staff get about US$2 or US$3 per day, while for porters and bellhops a tip of US$1 per bag is appropriate.