I live at home but pay for things such as my own food, gas, school supplies, etc. I don't however regularly pay any of the household bills. Does it count as my parents providing half of my support given that I don't pay any kind of rent to them?
Check with your parents to be sure they are not claiming you as a dependent on their return.
You figure whether you have provided more than half of your total support by comparing the amount you contributed with the entire amount of support that you received from all sources. This includes support you provided from your own funds.
You pay for: food, gas, school supplies, etc.
Your parents pay for: food--They feed you sometimes since you live at home, right? rent/utilities? tuition? clothing? Insurance?