Mix flour, baking powder, baking soda, salt, and sugar in a mixing bowl. Cut in butter or shortening with pastry blender until mixture resembles coarse crumbs. Add buttermilk. Mix quickly to make soft dough. Turn out onto lightly floured surface. Knead a few times to make a soft dough, don't overknead or the biscuits will be hard and dry. Roll out to a 6-by-6-inch square. Place on ungreased baking sheet. With knife, cut dough into dozen even portions. Do not separate. Bake at 400^ until golden about 15 minutes. Dust with flour, if desired when biscuits come out of the oven