He assumed you were talking about a coupon as you didn't specify whether it was automatic discount or a coupon
I'll use the Login As User mod to check this out on your account, as it's working fine for mine, sec.
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AJAX Threads Lifetime is 54.95 before discounts, your 42.5% automatic discount reduces the price to $31.59 which is what I saw the total price as when viewing your cart.
Do you see a different output? If so, please post a screenshot of the Checkout page