This sounds like church jargon with a phrase appropriated from the Bible to lend it credibility. It is not necessarily a bad idea but it crosses the line into false doctrine when it is claimed that it is a matter of God's "law" and must be complied with. This is a form of tithing that is inappropriate for followers of Christ. We are charged to give freely and not of constraint or by "law".
Tithing is an Old Testament practice and is not binding on believers today. Having said that, tithing is not a bad bench-mark to use when considering how much to give. Note that the tithe today would include any and all charitable donations not just those given to a church.
You must realize, however, that there is no mention of tithing in the New Testament. However the Bible does talk about tithing in the Old Testament. Here's a passage in the Old Testament, Leviticus 27:32 which defines the "tithe" "And concerning the tithe of the herd, or of the flock, even of whatsoever passeth under the rod, the tenth shall be holy unto the LORD." The word "tithe" in the Hebrew of the Old Testament and the Greek of the New Testament literally means "a tenth" which is 10%.
The "tithe" under the law of Moses is no longer in force for New Testament believers. Our offerings are the equivalent of "freewill offerings" under the law - these were voluntary and involved no set amount. In Christ, nobody has the right to tell us how much to give or to whom it should be given. In Christ, we acknowledge that all that we have belongs to God including ourselves, not just 10%.
Here is the New Testament standard of giving, Romans 12:1,2 "I beseech you therefore, brethren, by the mercies of God, that ye present your bodies a living sacrifice, holy, acceptable unto God, which is your reasonable service. And be not conformed to this world: but be ye transformed by the renewing of your mind, that ye may prove what is that good, and acceptable, and perfect, will of God." He wants us to offer ourselves which is our "reasonable service." The Greek word for "reasonable" is "logikos" and it means literally, "according to the word." It is only when we make our offering of dedicated serivce to God in accordance with His will as expressed in His word that our offering will be acceptable. You are only bound to give from the heart of that which God has blessed you in the work of your own hands.
Here is some information from the website on this topic:
I hope you have found this helpful.