cash box; money box
A box or container for keeping coins and small amounts of cash, often used in shops or at events.
I put the day's earnings into the shop's cash box.
縁日の屋台で、銭箱からお釣りを取り出す。
At the festival stall, I take change out of the money box.
Compound of 銭 (zeni, 'coin, money') and 箱 (hako, 'box'). The reading ぜにばこ follows rendaku voicing of はこ to ばこ.