I got hooked onto Ebates through my mother who uses it more than Airmilesshop.ca now.
Create you account on Ebates and then you can browse all the 'stores' through the Ebates site. The cashback percentage is also listed by each store name so you see what your best deals are there.
I purchased our trip on the Expedia.ca website THROUGH ebates.ca. At that time, Expedia was offering double cash back so I will receive 10% instead of their regular 5%.
Here's the catch... Ebates sends out cheques (or deposits into your bank account) every 3-4 months. You can check their schedule to see the pay table so you know exactly how much you'll be getting and when it will be sent.
I was expecting to receive my big fat cheque in May for our trip's purchase back in January HOWEVER, Expedia.ca doesn't credit your ebates account with the purchase until a few days AFTER you travel. This means I won't be receiving my cashback for my trip until March of next year. LOL.
Ebates is good, you get money for your normal spending habits, sometimes you can even get really good deals and free shipping!
At the time I purchased our trip, I did not know that my cashback wouldn't be applied to my account until AFTER our trip but that's ok, I still get back about $200 for it. I paid for the trip upfront though.
good luck, have fun!