OK, submitted by @idpsteve, here's a way to do it in Form Render Script.
$("input[id='zTotalPaid']").attr('tabindex','-1');
$("input[id='zTotalInvoiced']").attr('tabindex','-1');
$("input[id='TotalAmount']").attr('tabindex','-1');
$("input[id='fDolRemain']").attr('tabindex','-1');
$("input[id*='fLastBillDate']").attr('tabindex','-1');