Crumble one cake of yeast into a bowl. Add 2 1/2 cups lukewarm milk and stir until yeast is dissolved. In mixing bowl, cream 1/2 cup shortening. Gradually add 2 T. sugar and 2 tsp. salt. Sift 5 cups flour. Add 1 cup to mixing bowl, beat well. Add 1/2 cup yeasted milk. Beat well. Repeat until all flour and yeasted milk is used, beating between each addition. Continue to beat until dough is smooth, scraping bowl often. Cover with damp cloth and allow to rise in warm area (80 degrees) until double in bulk, about one hour. Punch down, stirring with a spoon. Drop by large spoonfuls into lightly greased muffin cups, filling them about 2/3 full. Cover and let rise again, about 20 minutes to double. Bake 20 minutes at 450 degrees. Makes 30 rolls.