Hi again Mabg
Sorry, I missed your post saying which approach you were interested in, that is challenging flying!!
On the subject of rounding; up to next 10ft in final segment; up to next 100ft in the intermediate segment, which must also include a 1.5NM level section for Cat C and D (1.0NM for Cat A and B) if there is a descent; and up to next 100ft in initial segment.
If you are using Excel for your calculations, I would suggest using the Radians() function to convert degrees to radians within your formula.
Cheers
TeeS