Item Selling Price fetch on total Order Quantity for Same Product

Hi All,

we have following requirement Customer order total quantity of item ABC 1000 nos.

business enter 1000 qty in following manner:

Line        Product      Quantity       Unit Selling Price                                   Price List Price break criteria           

1.1          ABC            100              10$                                                        0-200     = 10$

1.2          ABC            200              10$                                                        200-300 =  8$

1.3          ABC            300               8$                                                         300-999999 =  6$ <<<<<<

1.4          ABC            400               6$                            

                       Total= 1000

when Order Total Quantity reach to 1000 nos total order quantity final selling Price for each line should be 6$

Line        Product      Quantity       Final Unit selling Price when order reach to 1000 Qty

1.1          ABC            100                  6$

1.2          ABC            200                  6$

1.3          ABC            300                  6$

1.4          ABC            400                  6$

final order quantity should applied to all previous lines irrespective to Price break.

can we change price break logic of item qty range to total order sum quantity. or any other way to achieve it?