Haste Rounding Error Calculations Formular ?

as most know haste is not giving exactly the values stated on the gear.
this it due to it easier and less CPU heavy to simply do bitshifft rather than exact division

however i can't find a formula that calculator the exact same rounding

I did this:
GH = gear haste value (this example 2)

GH/100 (to get it into %) in this case 0.02
(GH/100)*1024 (to get it into "units)
then i round of the units which in this example is 20 units.

so i did this
units/1024 * 100 which should give me the percentage of that calculation

however i come a bit low value
1% GH = 10 units = 0.9 Real haste
according to wiki it should give 11 units and 1.07


so instead of using the value 256 i used 256
which gave me the exact 1.07 percentage on haste 1 items

However now its wrong on the higher haste values
E.G turban gives 5.078 real haste and not 4.88 as stated on wiki


what is the right approx to calculate this for all values ?

According to testing long ago most are simply haste*10 /1024. A few get an extra 1 added like 1% and 6%. Though when it was done there was no 7 or 8% so don't know about them.

It's probably cause it doesn't follow an exact formula

Tiercel was recently tested to be 10/1024, Blitz and Lancer's Pelerine might be 10/1024 as well. 7% is 71/1024 iirc, not sure about 8%.