While there are directions for giving in the New Testament, there is not a specific number or percentage. The concept of tithing (giving a tenth of your income or harvest) comes from a number of Old Testament passages that we can break into three distinct types.

1. Levitical Tithe

Numbers 18:21 - Behold, I have given the children of Levi all the tithes in Israel as an inheritance in return for the work which they perform, the work of the tabernacle of meeting. 

Verse 24 shows that the spirit of this gift was given to God out of worship, but it went to the provide for the Israelite priests and their families (the Levites) and to the care of the temple. This is the tithe churches point to for the biblical grounds of a tithe to your local house of worship. Before there were Levites, Abraham gave a similar tithe in Genesis 14:18-20.

2. Tithe of the Feasts 

Deuteronomy 14:23 - Eat the tithe of your grain, new wine and olive oil, and the firstborn of your herds and flocks in the presence of the Lord your God at the place he will choose as a dwelling for his Name, so that you may learn to revere the Lord your God always.

Verses 22 through 27 explain the entirety of this tithe, which is quite different from the first. There is an element of "self-care" or "sacred rest" here, where the tither enjoys the tithe themselves, out of thankfulness and worship to God. It's entirely biblical to plan a vacation or a celebration for your family, particularly if it's centered around reflection on God's goodness.

3. Tithe for the Poor

Deuteronomy 14:28-29 - At the end of every third year you shall bring out the tithe of your produce of that year and store it up within your gates. And the Levite, because he has no portion nor inheritance with you, and the stranger and the fatherless and the widow who are within your gates, may come and eat and be satisfied, that the Lord your God may bless you in all the work of your hand which you do. 

This is a tithe commanded to a community for the benefit of immigrants, orphans, widows and the occasional hungry Levite. There's the implication here that God's blessing goes hand in hand with justice and care for the marginalized in society.

Do these tithes directly apply to Christians? That's the subject for another article. Certainly, there are elements in each of these tithes that we can integrate into our practice of giving and saving. We close with a verse on generosity from Paul: 

 2 Corinthians 9:6-11

Remember this: Whoever sows sparingly will also reap sparingly, and whoever sows generously will also reap generously. Each of you should give what you have decided in your heart to give, not reluctantly or under compulsion, for God loves a cheerful giver. And God is able to bless you abundantly, so that in all things at all times, having all that you need, you will abound in every good work. As it is written:

Now he who supplies seed to the sower and bread for food will also supply and increase your store of seed and will enlarge the harvest of your righteousness. You will be enriched in every way so that you can be generous on every occasion, and through us your generosity will result in thanksgiving to God.