I'm with Andy -- a few spoonfulls of tomato paste will add the sugar lots of folk have recommended, thicken the sauce, and not make the sauce sugary sweet, just tomato-y sweet. I'm one of those "never the same twice" cooks, but this is always a good hint for tomato sauces (be it Italian for pasta or chili) if the tomatoes are too acidic or you've messed up and overpoured the wine. I also like to use "tomatoes in tomato puree" rather than just canned tomatoes. I had a bumper crop of tomatoes last summer, though, and a little tomato paste goes a long way. When you only need a spoon or two, the rest freezes quite well if you take it out of the can and put into a baggie.