I recommend this podcast interview with Thomas Kuhne, author of Belonging and Genocide: Hitler's Community, 1918-1945.
Kuhne claims that no German soldier ever faced court martial for refusing to kill a civilian. He estimates that (only?) about 200k German soldiers in total were involved in the killing of Jews or other civilians. But by the end of the war every German who wanted to know about "crimes in the east" could easily find out. This last observation is supported by letters and diary entries of ordinary people. Matters of national guilt or conscience weighed heavily on soldiers and ordinary Germans by the end of the war, Kuhne claims.
Kuhne makes interesting observations about the male social hierarchy within military units. Those who refused to carry out Nazi orders against civilians were regarded as weaklings, but were not subjected to direct reprisal.
There are two means to unite a people — common ideals and common crime.
—Adolf Hitler, Party Leader, Munich, 1923
If this Jewish business is ever avenged on earth, then have mercy on us Germans.
—Major Trapp, Police Officer, Poland, 1942
For there is a great, bright aspect to this war: namely a great comradeship.
—Adolf Hitler, Reich Chancellor, Berlin, 1942
We Germans are the nation that has gone for this war enthusiastically and will have to bear the consequences.
—Franz Wieschenberg, Wehrmacht Private, Eastern Front, 1944
To stick together and to fight side by side and be wounded side by side, that’s our wish.
—Kurt Kreissler, Wehrmacht NCO, Germany, 1945