A better question for followers of Jesus Christ to ask is, "What principle should govern my giving of the money/resources God has entrusted me with?" (I realize that question ends with a preposition, which is a grammatical no-no. Sorry. I couldn't think of a better way to word it.)
What does the bible say about the issue of giving? In the passage Sproul mentions Jesus does not condemn tithing, rather He condemns the hypocrisy of the Pharisees. Interestingly, however, Jesus does not tell us anywhere to tithe. In fact, nowhere in the New Testament do we see the church tithing. So what should we do?
Paul addresses giving very clearly in II Corinthians 9:6-7, saying. "The point is this: whoever sows sparingly will also reap sparingly, and whoever sows bountifully will also reap bountifully. Each one must give as he has decided in his heart, not reluctantly or under compulsion, for God loves a cheerful giver."
We see the early church practice this in Acts 11:27-30, "Now in these days prophets came down from Jerusalem to Antioch. And one of them named Agabus stood up and foretold by the Spirit that there would be a great famine over all the world (this took place in the days of Claudius). So the disciples determined, everyone according to his ability, to send relief to the brothers living in Judea. And they did so, sending it to the elders by the hand of Barnabas and Saul."
The early Christians understood that giving was a heart issue. II Cor. 9:6-7 makes it very clear that we must each decide what to give at any point in time. This is not to be done reluctantly or under compulsion, but out of joy.
If we want to be biblical people, we will give freely and joyfully. When we do this, we may not even know exactly how much we have given. We need to be "money in - money out" people (in terms of giving to those in need).
Why tithe when A) it is not a New Testament church practice, and B) it is not a joy-filled practice?
Sproul gets it wrong here. Let's give as Paul describes in II Cor. 9.