Can Autoinvoice calculate and apply discount to invoice line ? How ?

HI

One of the invoices lines is failing in autoinvoice error "The amount not matching with unit selling price times the quantity"

When we check with our customer we found out they had applied a discount of 5%   so  amount being passed in invoice line is  less than  quantity * Unit selling price

Now  is there a way we can handle this through autoinvoice ?  is there a discount column that can be populated for autoinvoice to calculate and apply discount while creating an invoice

OR

Please suggest a solution to handle this

Please respond asap

Thanks

Nitin