this one was a head scratcher, but i think I have it:
This is assuming you have a column that marks the product category. In my example, I using a column named "category", in the add to cart buttons, I'm giving it the value "cd" or "lp"
you need to create 4 rules using the Number Of Items with a specific column value trigger:
Name: 1 LP
Triggers:
Number of items where 'category' has a value of 'lp' is '>=' a value of '1'
Calculation:
Flat Rate: 13.99
Name: more than 1 LP
Triggers:
Number of items where 'category' has a value of 'lp' is '>' a value of '1'
Calculation:
Flat Rate:
($this->ConditionalTotal("Quantity", "category", "lp")-1) * 6.99
Name: 1 CD:
Triggers:
Number of items where 'category' has a value of 'cd' is '>=' a value of '1'
AND
Number of items where 'category' has a value of 'lp' is '<=' a value of '1'
Calculation:
Flat Rate: 8.99
Name: More than 1 CD
Triggers:
Number of items where 'category' has a value of 'cd' is '>' a value of '1'
Calculation:
Flat Rate:
($this->ConditionalTotal("Quantity", "category", "cd")-1) * 4.99 + (($this->ConditionalTotal("Quantity", "category", "lp") >=2)?4.99:0)