It is sad that so many relatively intelligent people cannot grasp the distinction between two related concepts.
Leaves fall to the ground, and rain falls to the ground, but leaves are not rain. A cello can give a pleasant sound, and a brook can give a pleasant sound, but a cello is not a brook. A textbook can tell its reader about history, and the Bible can tell its reader about history, but a textbook is not the Bible.
A person can give, and a person can tithe, but giving is not tithing. If Christians could get this simple distinction straight, and stop misusing the terms, it would resolve a large portion of the confusion on this matter.
Tithing, under the old covenant Law, was payable with agricultural products, not money. It was never voluntary. Giving, for the Christian, is not limited to agricultural products, and is always voluntary.
Giving ten percent of your monetary income is not tithing according to the Bible. Even if you were to give one-tenth of your crops and every tenth animal to your local church (imagine the uproar!), you still aren't tithing according to the Bible because the tithe is to be brought to the Levites at the temple, not to the pastor at the church building.
Giving of your financial resources to support your local Christian fellowship IS clearly implied in Scripture as a requirement of Christians. However, that's not "tithing".
Here's the core problem: the word "tithe" is NEVER used in Scripture of a voluntary offering of money to a religious institution. If you use the word, "tithing" to describe that practice, you will have people thinking that "tithing" is a requirement. They will look in their Bibles, find the laws about tithing under the old covenant, and feel either guilty because they aren't handing over enough, or prideful because they think they are. Neither is sound, because Christians aren't under the Law. God is not the author of such confusion!
Please, STOP calling your monetary giving "tithing". It's Christianese codswollop rooted in plain ignorance (and maybe some pride). Just give your money, and if you need a word to describe the practice, use the one that the Bible uses: offering.