Amount round off

Amount round off

I have a two fields :

1. Total Amout[Single Line],which will fetch from master as "INR 300"

2. Paying Amount[Decimal line],which the user will enter in form.
I can validate if both the values or not same.

But I can't validate the decimal amount in Total Amount field.

For Ex: If the Total Amount is INR 300.75

The user can enter either 300.75 or 301.But when user enters the amount as 301/300,the validation occurs.

I have used round function also still it is not working.

Anybody have any idea for this??

Thank you in Advance.