pricing procedure

Hi experts,

My client's requirement is the discounts and surcharges should be calculated on two parameters.

Based on the parameters entered at the time of GR, system should calculate a new factor through a formula.

If the factor is 10.00 no discounts/surcharges

If the facotr is less than 10.00, the unit price will decrease(discount) 70Rs. per 0.1decrease

If the factor is greater than 10.00, the unit price should increase (Surcharge) 70Rs per 0.1 increase

Could some one please guide me how to achieve the scenario.

Regards,