This is a rather long page chock full of info. The currency used in Fiji is the Fiji dollar. Despite Fiji's withdrawal from the Commonwealth, QE II's countenance shines brightly from Fijian currency.
Traditions die hard.
It never ceases to amaze me how often taxis seem to be short of the proper change and expect you to make up the difference. The same scenario might occur when bargaining for an item at a craft market. You will find that travelers' checks are readily cashed in any Fiji bank and in most hotels and duty-free shops. When traveling to Fiji it's best to bring a minimal amount of cash. Naturally you will want to take your credit card with you for hotel stays or big ticket items.