The Collaborative International Dictionary of English v.0.48:

cashbox \cashbox\ n.
   a box for holding cash.

   Syn: money box, till.
        [WordNet 1.5]

WordNet (r) 3.0 (2006):

cashbox
    n 1: a strongbox for holding cash [syn: cashbox, money box,
         till]

Moby Thesaurus II by Grady Ward, 1.0:

31 Moby Thesaurus words for "cashbox":
   Fort Knox, bank, bursary, cash register, chest, coffer, coin box,
   depository, exchequer, fisc, gold depository, locker, money chest,
   penny bank, piggy bank, pork barrel, public crib, public till,
   public treasury, public trough, repository, safe, safe-deposit box,
   storehouse, strong room, strongbox, subtreasury, till,
   treasure-house, treasury, vault