Vendor total in app. urgent please

Hi all,

Our client needs to pay the vendor total amount if exceeds Rs.20000/- they will print manual cheques.

If the vendor total (including all line items) less than 20000, they will pay through Telegraphic transfer.

For this in F110, i specified the amount in local currency in the tab additional selections. but it is taking line item wise below 20000. i selected this filed and i given like this (00000,20000).

which field i have to take for this?

Its urgent, kindly anybody give the solution....

Raghav