I am trying to calculate a discount price based on quantity purchased. For
example if someone buys 20 widgets they pay $4.00 each for them, if they buy
50 widgets they pay $4.00 each for the first 20, then $3.50 each for the next
30, 100 widgets - $4.00 first 20, $3.50 next 30 and $3.25 for the other
50..............

Any hope?