An additional tithe, collected every three years, was to be used to meet the needs of the Levites, foreigners, orphans and widows. (Deuteronomy 26:12-13). Additional tithes were taken for festival purposes.
In addition, everyone was to be generous with those in need:
If there is a poor man among your brothers in any of the towns of the land that the LORD your God is giving you, do not be hardhearted or tightfisted toward your poor brother. Rather be openhanded and freely lend him whatever he needs. (NIV, Deuteronomy 15:7-8)
However, Jesus made it clear that we are obligated to be generous to those in need (Matthew 25:31-46).
Give to the one who asks you, and do not turn away from the one who wants to borrow from you. (NIV, Matthew 5:42)
Giving is to be done cheerfully, rather than as an obligation (2 Corinthians 9:6-7), and not for the purpose of public recognition (Matthew 6:1-4). The amount to give is not necessarily ten percent (Matthew 19:21, Luke 18:22, 21:1-4, Hebrews 13:16, 1 John 3:17). Generous giving is an acknowledgment that everything we have is a gift from God, and is to be used in His service (Luke 12:33, Acts 20:35, 1 Timothy 6:17-19, James 1:17, 1:27, 1 Peter 4:10).
Rather than give a certain amount as an obligation, Christians are urged to share generously of whatever talents, abilities and wealth God has entrusted to them:
We have different gifts, according to the grace given us. If a man's gift is prophesying, let him use it in proportion to his faith. If it is serving, let him serve; if it is teaching, let him teach; if it is encouraging, let him encourage; if it is contributing to the needs of others, let him give generously; if it is leadership, let him govern diligently; if it is showing mercy, let him do it cheerfully. ( NIV, Romans 12:6-8)
There is nothing in the Bible saying we should give a certain amount or a certain percentage to a church.
Also, there is no requirement in the Bible to give "seed money" to a church, preacher or ministry, and no promise that any blessings of any kind will come as a result.
Related article: What Does the Bible Say About Generosity and Duty to the Poor?