The currency used in Nepal is the Rupee and to get the best exchange rates, it is best to stick to US dollars rather than Traveller's cheques or sterling and make use of the extensive Black Market in the country. Many shops in Kathmandu will accept US dollars and Indian Rupees without penalising you on price - particularly for more expensive purchases, and credit cards are becoming more widely accepted across the country as tourism increases, and although there are few ATMs in the whole country, you can usually get a cash advance in a bank - at a small charge.
Depending on what you do in Nepal, it can either be very cheap, or very expensive, independent trekkers get by quite easily on around £15 per day, but if you're doing it all properly, with guides, and porters, and permits, then the sky is the limit.
Tipping is increasingly common practice - around 10% of the bill on upmarket restaurants - a few pence everywhere else, unless a service charge has already been added to the bill, and gentle bargaining over prices is the norm in almost all markets, shops and hotels.
