וְאִם־גָּאֹ֥ל יִגְאַ֛ל אִ֖ישׁ מִמַּֽעַשְׂר֑וֹ חֲמִשִׁית֖וֹ יֹסֵ֥ף עָלָֽיו׃
And if a man will redeem aught of his tithe, he shall add unto it the fifth part thereof.
Read kabbalistic (mystical) interpretation of Leviticus 27:31: and classical mystical sources.