attack speed breakpoints?

Question: Are the attacks per second (cooldown) numbers listed in the tower specs menu an estimate or a set figure? For example: If it's an estimate, the actual firing speed of the tower would increase with every potion that it's given (ie. 0.1s is actually 0.06095 aps) If it's a set figure, the aps will remain the same for both a shadow with 0.1 aps (15 speed potions) and a blofield laser with 0.1 aps (150 speed potions). Leaning towards the set figure.

I'm more looking into ASPD% add. I guess the speed is rounded off/up

The attackspeed is increased with every single potion. On the stats screen it is rounded to 1 digit after the comma, that's why it seems that e.g. from 0.2 to 0.1 it takes some time that something happens to the attack speed in the stats screen. Under the hood its calculated continuously.