There is NO NT ECONOMY!!!! It's all about living in community and sharing with those who have less than you in that community.
Jesus said let the one who has two coats give one to the man who has none. That's 50%, not 10%. Yes, it seems Jesus and Paul were not looking so much for accountants as for lovers.
God gave the law as a means to check oneself. Not as a "you'd better do this or else," but "here's how to tell if you're walking with God." In the Old Testament, the Israelites turned it in to a chore rather than an expression of love. Long before Jesus came, the Prophets kept telling them (us) that God didn't want us just to follow the law by rote, memorizing things and doing our duty. "Oh, let's see, here's 10 shekels, so I put one in this box and now I don't have to think about God any more until next week." That is NOT what God wanted.
He sent the Prophets, and when that didn't work, he sent his Son, who had the same message, only it was "straight from the horse's mouth," as it were. If you're just going to go through the motions of obeisance and not follow God with your heart, God has no use for you. God would rather have you slip up from time to time, and then come to him in repentance for mercy, knowing that your heart is in the right place.
If you see the tithe as a burden, don't do it. God doesn't want you money if you have that attitude. If you see the tithe as a wonderful opportunity to give back to the community what God has blessed you with, God's love is made manifest in the world by your actions, Christ's light shining through you as a light to the nations.