Is there a way to figure out the exchange rate of one 1945 German mark to a 2016 Euro and/or U.S. dollar? (edited)
One Reichsmark is worth exactly zero Euros today as the Reichsmark is not legal tender. You can go to eBay to find out what the asking price is for collectors, banknotes seem to be going for about US$2 regardless of denomination while silver coins are going for about US$4-5 to the Reichsmark.
If you were in an alternate universe where the Reichsmark and Euro co-existed you would get a similar answer, but for different reasons. Prior to the German capitulation, you would not have been able to exchange Reichsmarks for Euros due to currency controls. After the capitulation inflation made the Reichsmark so value-less that commerce was done through barter. See Wikipedia for a brief overview.