The Collaborative International Dictionary of English v.0.48:

Cash register \Cash register\
   A device for recording the amount of cash received, usually
   having an automatic adding machine and a money drawer and
   exhibiting the amount of the sale.
   [Webster 1913 Suppl.]

WordNet (r) 3.0 (2006):

cash register
    n 1: a cashbox with an adding machine to register transactions;
         used in shops to add up the bill [syn: cash register,
         register]