Yes, the cubic centimeters after the 20th are half price if your model is "dense".
So for 64.88cm3 for instance you pay
$1.50 (startup) + 20x$1.50 (20 first cm3) + 44.88x$0.75
that is $65.16
In Sandstone it would have been $1.50+64.88x$0.99=$65.73 a little bit more expensive.