Heat oil in medium-size saucepan over medium-low heat. Add onion and garlic and cook, stirring occasionally, 10 minutes.
Add tomatoes and their liquid, tomato sauce, dried herbs, sugar, salt and pepper. Using clean kitchen scissors, cut tomatoes into bite-size chunks in pan.
Bring sauce to a simmer over medium-high heat, then reduce heat to medium and simmer 20 minutes. Meanwhile, in a large pot of lightly salted water, cook spaghetti according to package directions. Drain pasta and serve topped with marinara sauce.