Discount Modifier Calculation

Hello All

I am working for the first time on the modifiers and experiencing one problem.

When i apply a discount modifier on the header of the sales order there is a difference in calculated value and the actual value on the Sales Order .

For example

If the total price on SO is 1,269,000 and then i apply a discount of 64.5390070922% the value should be 450000, however it shows 451000. This happens with all the SO with different items too.

Could anyone help me on this as to how the calculation happens ?

Thanks in Advance

JY