Adjusting height doubt

[adetogni]

Hi, I started using Orux since a few weeks and the more I learn it (let's admit it, it's not easy!) the more I love it.

I have one question: after I make a hike, I come home and quite often I have to adjust the gps tracking because sometimes there are holes (gps not fixing, the battery saving switching off GPS...). So I add the points and follow what was my hike.
Then once I finished I do the "fix heights" (or adjust heights, mine is in Italian) to correct the GPS heights. There are three choices
- apply rounding
- use DEM
- use alternative online service

IF i use Apply rounding multiple times the total difference in altitude is always lowering. I understand that's because if you have -1,4 -> +1,4 -> -1,4 -> +1,4 on the normal hike the total positive is +1.4+1.4=+2.8, but if it simplifies to -1 -> +1 -> -1 -> +1 now it gets +2.
So the first question is...how many times the rounding should be applied and on which value (1,2,4...)?

IF instead I use the DEM files (sourced on the web and installed, i think they're the best), even more than once, the value is always the same and it's higher than the previous.

So for example the original track is +1000
-> apply rounding once becomes +900
-> apply rounding twice becomes +750
-> use DEM files becomes +1100

So...what is the best method to calculate most accurate hike positive altitude?

thanks