It varies. Right now it’s up to 3%. Walmart.com has gone as high as 10%.
ebates is great—use it a lot.
Even for travel and hotels.
Folks don’t know, and leave money on the table for purchases they would make anyway.
Walmart also has a program you sign up for, and submit pictures of your receipt from your smartphone. They look at what you bought, and if a competitor has a lower price, you get the difference.