'Adding' in the Bible

He must make restitution for his sin regarding any holy thing, adding a fifth of its value to it, and give it to the priest. Then the priest will make atonement on his behalf with the ram of the restitution offering, and he will be forgiven.

or all that concerning which he sweareth falsely, he hath even repaid it in its principal, and its fifth he is adding to it; to him whose it is he giveth it in the day of his guilt-offering.

If it is one of the unclean livestock, it must be ransomed according to your assessment by adding a fifth of its value to it. If it is not redeemed, it can be sold according to your assessment.