Zoho Invoice : Adding Discount amount instead of percentage

Zoho Invoice : Adding Discount amount instead of percentage

Hi,

 Is there a way I can enter the discount in amount, instead of mentioning it in percent terms? For example, if the price of book is $10 and, I sell it for $8. Can I enter "$2" as discount, instead of entering it as 20%?

I tried creating a custom template, but couldn't go very far. Any help / advice will be highly appreciated.

Thanks!