There are several cards that give 2% flat on all purchases. You can also do much better if you use specific categories across multiple cards, for example there are cards that give 5% for restaurants.
I'm dubious. I just glanced at my interchange plus billed Merchant Account Statement, and the highest I saw was 2.95% + 20 cents for a couple international business rewards cards. I suppose you could count this as 5% for an under $10 purchase, but do you have a specific example of a card that exceeds 4% on larger transactions?
