Place tomatoes and juice, sugar, salt and pepper in saucepan and bring to a boil.
Combine onion and margarine mixture and toasted bread crumbs, mixing well. Combine with tomato mixture and place in lightly greased pans. Top with crumbs, Parmesan cheese and melted margarine. Bake for 30 to 40 minutes at 375 degrees F. Bread cubes will absorb excess moisture; top should be nicely browned.