The answer to this fundamental question appears to be obvious and straightforward. Nazis and their allies (the Axis Powers) grossly violated one of God’s commandments – ‘You Shall Not Kill’ by murdering millions of Jews and individuals of other nationalities.
However, this is only one side of the matter. There is another side. On the Easter front, Germany and its European saved the Christian Church and the whole Christian civilization from being destroyed (annihilated, actually) by the Bolshevist Soviet Union.
Sending the “soldiers of God” (who they essentially were) who won the “holy war” (which in many aspects it was) to Hell would have been grossly unfair and thus highly unlikely.
Consequently, although we can never be 100% sure where the particular soul ended up in the afterlife – in Heaven, Hell or somewhere else – it is highly unlikely (practically impossible) that Nazis that made a contribution to victory in that existential war went to Hell.
It is far more likely that their souls currently reside in Purgatory or, possibly, in an entirely different place which is neither Heaven nor Hell (the Valhalla of sorts).