ATMs are common and it's easy to exchange money. Credit cards are accepted at more expensive establishments.
Restaurants Tipping a set percentage is not expected in Bali, but if service is good, 5000Rp or 10% or more is appropriate.
Services Hand cash directly to individuals (drivers, porters, people giving you a massage, bringing you beer at the beach etc); 5000Rp to 10,000Rp or 10% to 20% of the total is generous.
Hotels Most midrange and all top-end hotels add 21% to the bill for tax and service.