Heat olive oil in a saucepan at medium heat. Stir in the garlic, oregano, and rosemary. Cook for about 30 seconds. Add the tomatoes and sugar, bring to a simmer, and cook until the juices have reduced significantly and you have about 3 cups of sauce, about 20 minutes. Remove the sauce from the heat and set aside. Alternatively, you can use sauce from the jar and add your own meat and sauteed veggies to it.