How are variants and products treated concerning discounts

Hello all,

our client wants to sell their fonts digitally. He wants to grant a discount for each font face somebody buys: The first font face always costs the same, if you buy a second one, you’ll be granted 15% off, if you buy a third one you’ll be granted 20% off and so on.

Is this possible with Snipcart? I think A percentage rebate on the order total with the rule When a product is added a number of times could be used for that, but from the documentation I do not understand, how products or variants count towards the rule? Are different variants of the same product counted once or each individually?