Combinations of products

For example:



Item 1 ----------- 1$

Item 2 ----------- 1$

Item 3 ------------ 0.5$



After the description of Item 1, you can see:



Item 1 + Item 2 — 1.5$

Item 1 + Item 2 + Item 3 — 2.25$



And so on…

I would love this as well.



But by category groups and the option of % off.