Tithing Laws in the Bible

Leviticus
27:30
The land's tithes, whether of the crops of the soil or the fruit of trees, belong to God, and are thus consecrated to God.

Deuteronomy
26:12
When you have finished taking all the tithes of your grain for the third year, which is the special tithe year, you must give them to the Levite, and to the foreigner, orphan and widow, so that they will eat their fill in your settlements.

Merriam Webster Dictionary
1: to pay or give a tenth part of especially for the support of the church
2: to levy a tithe on
intransitive senses: to give a tenth of one's income as a tithe

Encyclopedia Britannica
(from Old English teogothian, “tenth”), a custom dating back to Old Testament times and adopted by the Christian church whereby lay people contributed a 10th of their income for religious purposes, often under ecclesiastical or legal obligation. The money (or its equivalent in crops, farm stock, etc.) was used to support the clergy, maintain churches, and assist the poor.

The common practice today is to give 10% of one’s net income to charitable organizations.  According to many Rabbinical authorities, giving more than 10% is admirable if possible, but one should never neglect their obligations to their home, their family and to oneself.