The old testament is often type and shadow of what is to come. God's word is eternal therefore if a principle is established in the Old testament, there must be a corresponding action in the New Testament if it is to be called a principle. If Jesus was a priest in the order of Melchizedek. How can tithing not be a New Testament principle? How can we separate that action? I wonder if the tithing of the Old Testament is type and shadow for a New Testament principle so i am asking for the full picture of what was practiced.
Also, Paul was apostle to the gentiles. He encouraged they who had no teaching in Judaism, to give to his support. He did not teach them to participate in the Jewish tithe. What was customary?