We also use one of our supermarkets credit cards that gives reward points, $1 = 1 point, we hit 20,000 points we get a $100 eftpos card which is in our case about every two months, 55 days interest free and we always pay on time so to date no interest.
The supermarket and it's allied stores offer bonus points on some purchases the best one being their liquor store which every so often offers 4000 points for a $70 purchase, one bottle of single malt and I'm there with points to spare.
If their fuel is cheaper I will use that too.
Some bonus points are simply not worth it so you have to be fairly judicious with your choices.
We have two major supermarket chains and they offer similar cards, the downside is the interest rate is high if you don't pay on time which is how they make their money, both close to 20%.