When shipping discounts are applied in cart or checkout, they are done in real time through our current system. Currently the system does not display what the original shipping quote and a new discounted quote to compare the savings to. Instead it shows after the discount is applied. We asked the developers of our business shipping app to include comparison amounts in future updates.
One way to confirm the discount is working for you is to visit your shopping cart with less than $40 subtotal. You can see the shipping cost without the discount. If you add another item in your cart that exceeds the $40 subtotal, the discounted shipping rate should appear.