You can use foreign bank cards at some places in all major cities in the region, including Xian, Ürümqi, and Lanzhou. Credit cards are not accepted outside of big hotels. The farther away you get from metropolitan areas, the less likely it is that your card will work in a local ATM. Have a supply of cash to avoid getting stranded. Traveler's checks can be cashed and foreign currency converted at Bank of China branches and major hotels. Tipping is unnecessary in restaurants and hotels: some more expensive hotels will add a service charge, but there is no need to add anything extra.