Gotta agree with Gooch here.
70% (meathead math) vs 72% (.80 x .90)
At the end of the day, the fact that plates weight 5, 10, and 25 pounds will decide what the "actual" percentage is.
The numbers and percentages used in 5/3/1 are like mind control to make you use around 75-85%, for reps around 10/6/3. Higher percentages look cooler, so the "Training max" is used to back things off a little. There's nothing wrong with that! It's the best way to "convince" new guys to use productive ranges. The whole program uses auto regulation, training by "feel", and the wave loading scheme, complex stuff, right from the beginning. It's like an easy way to introduce advanced concepts. It's genius!
The magic isn't the numbers. It's the way the numbers can guide anyone, even beginners through such an advanced training method, without really understanding "how" it works.