Preheat oven to 350. Spray a 13x9 inch-baking dish with nonstick cooking spray. Cook pasta according to package directions. Drain; rinse with cool water. Let pasta dry on paper towels. In a medium bowl, stir together 3 cups of the mozzarella with the ricotta, parsley and sugar. Using a pastry bag, carefully stuff pasta shells with prepared cheese mixture. Spoon 2 cups of spaghetti sauce into prepared baking dish. Arrange stuffed pasta over sauce. Pour remaining sauce over top of stuffed pasta. Sprinkle with remaining mozzarella. Bake manicotti for 15 minutes. Sprinkle with the Parmesan and Romano cheese; bake for 10 minutes longer. Serve immediately.