Amazon gives non-Prime members free shipping at $35 or more of eligible items. Instead of simply letting users get the product with free shipping, they’ve added a discount that prices it exactly one cent below the $35 limit, while only subsidizing the price with $3.38, which is about half of what they’ll then charge you for shipping.
It’s not too bad if you avoid all third-party sellers and only buy items sold by Amazon directly.
Unfortunately, other stores are going in the same direction. Walmart’s and Target’s sites both have third-party sellers on them now too, and you need to remember to filter them out.