When Jesus came to live among us, He found the Pharisees counting and tithing even tiny garden seeds. While He did not approve of their legalistic religion, He gave approval to tithing:

“Woe to you, teachers of the law and the Pharisees, you hypocrites! YOU GIVE A TENTH of your spices—mint, dill and cummin. But you have neglected the more important matters of the law —justice, mercy and faithfulness. YOU SHOULD HAVE PRACTICED THE LATTER, WITHOUT NEGLECTING THE FORMER.”
—Matthew 23:23.

The tithe belongs to God and is to be used exclusively for supporting Christ’s ministry and finishing His work on earth so He can return.

“The Lord has commanded that those who preach the gospel should receive their living from the gospel.”
—1 Corinthians 9:14.

“And this gospel of the kingdom will be preached in the whole world as a testimony to all nations, and then the end will come.”
—Matthew 24:14.

How much should we give in “offerings”?

“A generous gift, not as one grudgingly given. Remember this: Whoever sows sparingly will also reap sparingly, and whoever sows generously will also reap generously. EACH MAN SHOULD GIVE WHAT HE HAS DECIDED IN HIS HEART to give, not reluctantly or under compulsion, for GOD LOVES A CHEERFUL GIVER.”
—2 Corinthians 9:5-7.

Offerings are a matter of individual decision. They are used for financing the spread of the gospel in addition to the tithe which is used exclusively to support the gospel ministry.