donation box; contribution box
A box or container for collecting monetary donations, often seen at temples, shrines, charity events, or fundraising campaigns.
I put an offering into the donation box at the shrine.
賽銭箱 specifically refers to the offering box at Shinto shrines or Buddhist temples, whereas 献金箱 can be used in broader contexts.
Compound of 献金 (けんきん, 'donation') and 箱 (はこ, 'box'), with rendaku voicing of はこ to ばこ.