Calculate 90th Percentile formula calculation

Hi Folks,

I am bit confused with 90th percentile formula calculation in power bi and normal percentile formula calculation. Could you please advice which one should i go with.

Example :- This is the below column I wanted to calculate the 90th perncentile for the below range of values.

I am using the Dax = Percentile.Inc(Table[Time(in minutes),0.90) --> 88.1 is my 90th percentile output.

Normal Percentile Calculation :-

For n=90

F= 90*4/100=3.6, rounding up = 4

Then TTD 90 percentile = 95(because my 4th index value is 95) 

Based on these can you tell me which is the right value and If i have to implement the normal percentile calculation in powerbi how can i acheive this using measure.

Thanks for your help!