Tomatoes need to be either water bathed or pressure canned, depending on what else is in with them. As a general rule of thumb, you should process your jars per the least acidic vegetable or use a USDA approved recipe which has been tested for safety. When I used to process tomato sauce, I would pressure can the jars because I also added onions, peppers, and celery to the sauce. This may have been over-cautious, but I usually took a better safe than sorry approach. There has also been some concern about the safety of water bathing low-acid tomatoes - I'd do a web search to see what the latest thought is on that (my go-to Ball Blue Book for Canning/Freezing is from 1986 and woefully out of date).