$form->{"tax_$i"} = $form->{"amount_$i"} * $form->{"taxrate_$i"};
$form->{"tax_$i"} =
$form->round_amount($form->{"tax_$i"} * $form->{exchangerate}, 2);
$form->{"tax_$i"} = $form->{"amount_$i"} * $form->{"taxrate_$i"};
$form->{"tax_$i"} =
$form->round_amount($form->{"tax_$i"} * $form->{exchangerate}, 2);