Osaisen

A shrine or temple has a large box called “Saison-bako” set up. People throw money there when they make a wish to God or Buddha. This custom is “Osaisen(お賽銭)”.

The amount to be charged is not decided, but many people like 5 yen coins. This is because 5 yen is said to be suitable for Osaisen. Because “5 yen” is the same pronunciation as Japanese as “Go-en” representing connection and relationship.

5yen coin. 5円玉
5yen coin

But those who expect big returns seem to throw a larger amount.