Read Proverbs3:9-10 (http://bit.ly/2PlmXiZ)

Wealth, money, stuff – don’t put it above God – don’t make it your idol.

When we give to God, we’re showing God that He is above this and we value Him above money. We are also showing that we don’t put our trust in money or stuff but we’re putting our trust in God.
Giving to Godis alsoa Biblical principle, by which you should live.

For example, if I were to get R50 from my parents a week, I’ll tithe R5 (which is the10%) and then perhaps give a further R2 as offering.