Start canning tomato sauce by washing seven 1-quart canning jars and lids with soap and rinsing them with water. Place the jars, lids and rings in a canner with simmering water to sterilize them before adding in the tomato sauce. When sterilizing the jars, allow them to fill with the hot water in the pot.
Prepare the tomato sauce by blanching between 35 and 46 pounds of Roma tomatoes in a pot of boiling water. After only 60 seconds, transfer the tomatoes to a sink or container filled with ice water, and allow them to cool. Cut a slit in the tomato skins, peel them off, and cut out the tomato cores. Chop the tomatoes, and cook them in a pot at medium-high heat, continually stirring. Once the tomatoes start to break down, bring them to a boil, and reduce the heat until the tomato sauce thickens.
Pour 2 tablespoons of lemon juice and salt and sugar to taste in each of the seven sterilized jars, and fill them with the tomato sauce, stopping 1/2 inch from the mouth of the jar. Agitate the jars to release any air bubbles, and add the lids and rings. Place the jars back in the canner, covered with water, and bring the water to a boil for 40 minutes. Remove the jars from the canner, and allow them to cool for 12 hours before storing them.