To many tithing a tenth of income is an Old Testament teaching that comes out of the law because when Jesus came, he formed a new covenant. Moreover, 2 Corinthians 9:6&7 talk about sowing and reaping according to what we give, but ultimately we should give according to what we have decided in our heart to give.
So what should guide us? Some say the tithe should be the starting point. Others say that when Malachi talked about giving to the storehouse, it no longer refers to giving to the church, but to any worthwhile Christian endeavour (parachurch).
The new covenant is predicated on Jesus Christ. In Hebrews 7 it talks about Jesus being a priest in the order of Melchizedek. Moreover, it talks about how Abraham gave a tithe to Melchizedek, who was a priest forever, not from the line of the Levites. It goes on to say that Jesus is like Melchizedek, “and when there is a change in the priesthood, there is also a change in the law”v12.
The change in the law is not what or how much we give, however, but rather that we no longer need to go through the rules of an imperfect law that does not lead to perfection and that is tended by mortal priests (Levites). We are now led by a new priesthood, one that is eternal and is the way to perfection and eternity with God.
I think the sub-point here is the tithe, but it is a significant sub-point. It is a new testament reference to the fact that Jesus, the head of the church, is a priest in the order of Melchizedek, and as such is worthy of receiving our tithe as Melchizedek was worthy to receive it from Abraham.
Is the tithe part of the new covenant and strongly referred to on the New Testament? I think quite clearly yes. But don’t take my word for it. Read Hebrews, the whole book, but chapter 7 in particular. Let the Holy Spirit confirm or refute the truth of this assertion in you!