I hope it isn't too late for you op;
If you're making a reasonable amount of sauce (probably more than 2 servings), let that boi simmer on low for a good 45 minutes at least. Don't listen to the others, sometimes sugar is necessary to cut acidity when you don't have time to simmer for longer or for when you use 2 whole cans of tomato paste.
I have a 3 gallon sauce pot that I use for bolognese sauce when making a week's worth of meals, and I'll probably only put maybe a teaspoon of sugar in there. Granted I like to simmer it for 3 hours, but you can make the same thing in 45 minutes if you use maybe 2 tsp of sugar.
Too much sugar won't make the sauce taste bad, but you start killing your other flavors that you can preserve by letting the sauce cook longer instead. The longer tomatoes are exposed to sustained heat, the less less acidic they become, probably because of enzymes denaturing or some shit.
Don't forget to stir your sauce FREQUENTLY: shit burns on the bottom.