Editing WPForms total using jQuery

Question

I am trying to use jQuery to edit the total price shown in WPforms. This isn't really 'code' but this is the gist of what I'm trying to do.

if (fielda = "couponcode" ) {
 total - 50.00 = NewTotal
if (fieldb = "couponcode2" ) {
 total - total(1.00) = NewTotal
}