The obligation to tithe (i.e., to give 10 percent of one’s gross income) was binding only on the Jews. Jesus fulfilled the Mosaic law (Matt. 5:17), so even Jews are no longer bound by it. But this doesn’t mean we’re not obligated to support the Church—we are—but there is no longer a specific percentage required.
Scripture provides insight on how Christians should give:
On the first day of every week, each of you is to put something aside and store it up, as he may prosper. (1 Cor. 16:2)
The point is this: he who sows sparingly will also reap sparingly, and he who sows bountifully will also reap bountifully. Each one must do as he has made up his mind, not reluctantly or under compulsion, for God loves a cheerful giver. (2 Cor. 9:6–7)
There is no mandatory requirement to give a specific amount of money or percentage of our income. We should each decide for ourselves how much to give and then do so in the true spirit of giving a gift.