The currency used in the Maldives is the Rufiyaa, although in all of the resorts, all major credit cards are accepted for payments.
Tipping is not encouraged in the Maldives, although if service is particularly good, then it is increasingly common to leave a small amount of money or to round the bill up. Many of the resorts already include a 10% service charge in bills, and this will be added to the price of any meals that you order.
The only place where bargaining is welcome is the Singapore Bazaar in Male itself, although even there it is relatively unusual top get any discount on prices.
Meals in the resorts are not as cheap as other places you may visit as due to the nature of the hotels, everything has to be imported specially, although in Male itself, prices are lower.