Tiered Discounts [Support Thread]

A self-contained order_total encapsulated plugin for Zen Cart 2.1.0+ that dynamically applies discounts based on a customer's net cart subtotal.
Allows a fixed value discount and a percentage-based discount against the order subtotal.

Github: https://github.com/zenexpert/TieredDiscount

I have not tested this module on my test site yet, but is the code written to display/show the discounts on the shopping cart page as well as the checkout page?

It's your standard order-total module, no extras added. If you're outputting the ot block on your shopping cart page, it will be shown there. If not, it won't. It does display on checkout pages, of course - it's no different from any other order_total module.
I must admit I was thinking of throwing in an observer to display a message on shopping cart page (like "Add £15 more to your cart to unlock a 10% discount!"), but then that also needs a config switch etc so I decided to just KISS...