I need modul to my opencart system 2.1.0.1 which could make discount or special for more product in one group:

Special called “AKCIA 3+” is about if you buy 3 or more product you get special price. More products means more kind of products.

Example 1:

I have product A,B,C,D,E,F same Full Price 5€/1pcs, same Special price 2€/1pcs

1 x A = 5€

2 x A = 10€ (1-2pcs 3€/1pcs)

3 x A = 6€ (3 x 2€/1pcs)

A + B = 10€

A + B +C = 6€

2xD + 3xE + B = 6 x Special price = 12€

Example 2:

I have product L, M, N, O different Full price:

L=3€

M=5€

N=6€

O=9€

and also different Special price:

L=1€

M=3€

N=5€

O=7€

Rules are the same, but special price will be different at the each product, which is defined in Price field (f.e: 5,37€)