A couple of things:

a) Please resubmit without MIT license.

b) This doesn't work in my environment with OPC or standard checkout:

- At a minimum, you need to wrap the script that sets the value in
jQuery(document).ready(function(){

- At load time (in this environment), the total value is not what is shown on the screen (shipping tax has not yet been added and there are local taxes).
This is only an issue if the total is less than the GC amount.

- You may need to use

$orderTotalPlugin = round($order->info['total'], 2);