Discount when ordering a certain quantity

[Coen986]

I want to create the following situation in a (b2b) shop:

In our stock we want to give customers a discount per item if they purchase a complete box (with pe. 6 items). I'm searching for a way to implement that.

 

I've tried it by adding a quantity discount, but if customers order 7 items they should get discount for 6 items and full price for 1.

 

I've tried it by making a quantity atribute and adding it as a combination, but that gives me problems in stock management because single items and boxes are different products.

 

I've tried it bij making a package product, but than I'm creating two products for each product. That's not what I want.

 

Is there maybe a simple solution I'm missing??