You give to God because He gave you Him. You give to God because He gave you heaven, ability to praise and move, and a love for people. Basically because He gave you everything we need.
Whether it's money, praise, or thanks, we all can give to God. Sometimes we give less then what's needed, less than what's required of you. Sometimes we give a just fair amount and sometimes we give more than what's needed. There shouldn't be this many cases on giving. You should only be either giving a just fair amount or most importantly, more than what's asked.
To help you understand, think of a local charity program. The whole idea of the program is to help cure or help something in the world. In order to do that though, they need funds to help that. That's where you as a human comes in. You decide to go give something to help that cause. Two things happen. You either give too little and that program fails and you don't have any consolation that the cause is okay, or you give too much and it prospers more than it ever did. Thanks to people like you
Give too little to God, He gives you little. Give too much to God, He gives you more and more!
Give your offering. You can do it. You don't have to do less than what's asked, you can do a little more.