How do you get one key for 5 different locks?

You have a few options. One, you can change out all of the locks with the same type of lock of which a master key can be made for all of them. The other is to change them out with the exact same lock which the same key will unlock each one. If these are padlocks, you can go with a combination lock which you can get changed to the same combination for all of the locks.