scales basing on weight

Dear Experts,

we have a special requirement that scales need to be implemented basing on weight.

the requirement is as follows

5000 kg to 10000 kg -- 25 ps/kg

10001 kg to 30000 kg --- 30 ps/kg

the weights of the above scales shall be applicable on monthly sales basis not on individual sales order basis.

how to achieve this requirement in standard.

Thanks in advance

Regards

PK