The idea of giving a tithe (10% of your income) comes from the Old Testament. Christians are not under that covenant.
What the New Testament teaches is that we are to give a portion of our prosperity. "On the first day of the week let each one of you lay something aside, storing up as he may prosper, that there be no collections when I come" (I Corinthians 16:2). That is not a portion of our gross earnings. God is looking for people to give because they want to give, the actual amount is not fixed. "For if there is first a willing mind, it is accepted according to what one has, and not according to what he does not have" (II Corinthians 8:12).
If this be true, then what about Malachi 3:7-10, especially verse 9 and being cursed with a curse? Please explain.
"Yet from the days of your fathers you have gone away from My ordinances and have not kept them. Return to Me, and I will return to you," says the LORD of hosts. "But you said, 'In what way shall we return?' Will a man rob God? Yet you have robbed Me! But you say, 'In what way have we robbed You?' In tithes and offerings. You are cursed with a curse, for you have robbed Me, even this whole nation. Bring all the tithes into the storehouse, that there may be food in My house, and try Me now in this," says the LORD of hosts, "If I will not open for you the windows of heaven and pour out for you such blessing that there will not be room enough to receive it" (Malachi 3:7-10).
First, you need to notice that you have selected an Old Testament passage. You would first need to establish why the Old Testament should be binding on Christians when God said, "Behold, the days are coming, says the LORD, when I will make a new covenant with the house of Israel and with the house of Judah - not according to the covenant that I made with their fathers in the day that I took them by the hand to lead them out of the land of Egypt, My covenant which they broke, though I was a husband to them, says the LORD" (Jeremiah 31:31-32). And Paul warned, "Stand fast therefore in the liberty by which Christ has made us free, and do not be entangled again with a yoke of bondage. ... You have become estranged from Christ, you who attempt to be justified by law; you have fallen from grace" (Galatians 5:1,4). See "Why We Don't Follow the Old Testament" for more details.
You can see this in the passage you cited. It is directed at a single nation (Israel). It states that this nation has been constantly going astray (which Israel had). It talks about bringing in the tithes and offerings, the latter is a reference to sacrifices given by Israel. If you want to bind tithing, then why aren't you mentioning the need to bring in grain offerings and first-fruit offerings. It also talks about "My house," which is a reference to the temple in Jerusalem. It is interesting that you selected only a sliver of this command and want it applied to Christians while ignoring all the other aspects that show it is an integral part of the Old Testament law.
The passage does have its use. "For whatever things were written before were written for our learning, that we through the patience and comfort of the Scriptures might have hope" (Romans 15:4). It lays down the principle that if we put God first and obey His commands then we need not worry about the impact obedience has on our family. God will see to it that we are generously blessed. Such is also brought to our attention in the New Testament. "But seek first the kingdom of God and His righteousness, and all these things shall be added to you" (Matthew 6:33).
Such is what Paul stated would happen for Christians as well. Though a fixed amount is not set for Christians and God wants contributions that are voluntary, He also urges Christians to be generous. "But this I say: He who sows sparingly will also reap sparingly, and he who sows bountifully will also reap bountifully. So let each one give as he purposes in his heart, not grudgingly or of necessity; for God loves a cheerful giver. And God is able to make all grace abound toward you, that you, always having all sufficiency in all things, may have an abundance for every good work" (II Corinthians 9:6-9). Thus a similar promise is made to Christians which was made to the Israelites but stated in terms of Christ's new law. Give generously and happily to God and He will give back more than you could expect in return.