Shipping rates per number of products

Hi! I’m trying to set up a shipping rate structure for a client but I can’t find the way!

She sells greeting cards and wants to charge a $2.75 shipping fee for the first card + $0.25 for each additional card up to 4. Then for 5 cards or more the shipping fee will be $5.50.

I have a couple of problems I don’t know how to solve:

1) For now, I have 2.50 + ( 0.25 * [qty] max_fee=”3.50”)
That’s great for up to 4 cards but how can I add that gap from $3.50 to $5.50?

2) She sells many different cards on her shop and the idea is that the clients can combine them. How do I avoid charging a $2.75 shipping fee for each different card in the same order?

Thanks a ton in advance!