Supreme ego + purity of Fire : Max res calculation

Hi
I just did some testing with supreme ego and purity of fire. I assume this will not function correctly for all purity skills.

I thought the formula to calculate the max res gain should be:

RoundDown { [aura +max res] * (1 + [sum of all increase aura effect]) * (1.5)}

that would result in following threshholds for increased aura effect :

flat incr % result round
4 17 7.02 7
4 34 8.04 8
4 50 9 9
4 67 10.02 10
4 84 11.04 11
4 100 12 12

After playing around I noticed however that the threshholds are wrong. I suspect the implemented function is:

RoundDown { RoundDown { [aura +max res] * (1 + [sum of all increase aura effect])} * (1.5)}

Causing the +max res value to first be rounded down before the more multiplier is added. This results in threshholds to be equal to the increased multiplier resulting in the following threshhold table:

flat incr % result round
4 25 7.5 7
4 50 9 9
4 75 10.5 10
4 100 12 12
4 125 13.5 13
4 150 15 15
4 175 16.5 16

I did observe threshhold out of the 2nd table, but did not extensively test. I only have so much regret orbs.

It leaves me with the following question, Is this extra rounding intended behaviour?