DIscounts on Pro formas and quotations

There is an area where discounts can be added to orders, proformas and discounts - this only allows the entry of a percentage discount with two decimal places. Sometimes users wish to record a more precise discount:- eg. Say the order value is £5,123.76 and it is decided to give the customer 53.76 discount taking the price to £5,070.00. You cannot get exactly to that figure using the discount entry at two decimal places On a sales order a negative free text line could be used recorded the value exactly, but this is not available in proformas or quotations and it is difficult to understand why that should be? The only other option would be to provide 5 decimal places on the existing discount percentage entry area on all sales documents