The currency is the Czech crown (Koruna česká, or Kč). Euros do not circulate. ATMs are widely available, and credit cards are accepted almost everywhere.
Hotels Porters expect 20Kč to 50Kč per bag in top-end hotels; not typical for cleaning staff.
Restaurants Normal practice is to add around 10% if service has been good.
Pubs and bars For table service, round up to the next 10Kč (or 20Kč for bills over 200Kč).
Taxis Tips are not normally expected, but 10% if the driver helps with bags.