Preheat oven to 350°F. In large pot, boil cabbage leaves in water until tender. Drain cabbage and set aside. In a frying pan, brown meat with celery and onion; drain excess fat. Add rice, tomato, ketchup, egg, and salt and pepper. Mix well. Divide meat mixture among cabbage leaves. Roll up and tuck ends of each leaf and place, seam-side down, into 13"×9" baking dish. Combine tomato sauce and sugar. Spoon over rolls. Cover with foil and bake for about 45 minutes. Remove foil; sprinkle cabbage rolls with cheese and bake, uncovered, for another 5 minutes.