I use my credit cards to make money. I have no idea what the interest rate is, because I never pay any interest. I always pay my cards off in full each month.

My husband has a Chase credit card that pays him back 3% from home improvement stores (up to $2000) each month.
I was using a capital one quicksilver card which pays me bac 1 1/2% on any purchase each month.
I charge things that I usually pay cash for each month, like my electric bills and my many car insurances. I check first to make sure that they do NOT charge me 3% to use my charge card. (Like they do if you are paying your property taxes with a credit card.) That would completely defeat my purposes. But, My electric bills and insurance payments do not charge a fee.
I immediately put the cash I would have spent in an envelope and when the charge card bill comes in, I pay it off in full.
This month, I earned $42.68 from quicksilver and $60.51. I get these back in the 1) actual check and 2)deposit to my checking.
As you can see, I have earned over $100 this month, just for using my charge cards.

That is the only way I would reccommend that anyone use charge cards!