Tithing edible things was required under the Law but not under Grace. It was never about money! Make no mistake, money did exist during this time. In fact, God commanded the children of Israel to pay a mandatory amount of money as ransom for their lives. But it was not used in or for tithing.
Going from the Law to grace is not easy to understand. The Law required works and strict observance of ceremonies, rituals, and special days. Under grace, you are set free from ceremonies, rituals, and the observance of special days. Jesus fulfilled (completed) the demands (requirements) of the Law and came to offer us God’s gift of undeserved grace.