Can I do something like 4 in a $100 ?

Hi,
I’m looking for a way to give my customers a solid price if they are buying X pieces from any product.

For example, a customer is putting into the cart 4 products (each one has a different price) and the price for all of them together will be $100.
The fifth product price will be calculated normally and will be added on top of the $100.

Can I do it with your plugin?

The page I need help with: [log in to see the link]