Cream the shortening and sugar in a large stand mixer. Add the eggs one at a time, beating until fluffy. Add the molasses, salt, soda, ginger, and cinnamon. Mix completely. Add the flour, one cup at a time. The dough will become very stiff, and the bowl will be quite full. Once the flour is incorporated, turn the mixer off. It is a very stiff dough, and the object is to incorporate the flour, nothing more.