buy 2 get 1 free

[Guest]

I am looking for a contribution that lets you buy 2 of the same products and gives you one of the same product free.

 

I have looked at dangle the carrot but it does not seem to do that. All i want is for the free product to show in the shopping cart and there invoice

 

example if your shopping cart contains

 

2 blue widgets you will get one free

3 green widgets you will get 1 green widget free

4 purple widgets you will get 2 pruple widges free

 

any sudgestions would be gratfully recieved

 

Thanks