I would recommend that you contact your nearest Cooperative Extension office for the safest canning recommendations for your location and altitude.  It is vitally important for your safety to use up to date directions.  The acidity added to each jar, the size of the jar, and the processing times are all critical.  A beautiful-looking jar of home-canned tomatoes can easily harbor deadly botulism if proper canning directions are not followed carefully.  Grandma's recipe can be a killer as our soils and tomato strains have changed over time.  Using an out-dated canning book can also be inaccurate, so if you choose to purchase a canning book, make sure that it is updated and reliable - such as the Ball Canning Book, this years publication.  Avoid older cookbooks/guides.  Happy canning!