Andy, I'm surprise you have such a difficult time if you use Romas.
I gave up cutting tomatoes with my favorite chef's knife, and have been using my cheapie "ginsu" type serrated knife as mentioned above.
That was until I finally found a great diamond honing stone. It was at Walmart for about $15 and it has a course side and a fine side.
A few swipes with that and I'm able to filet farts without so much as a whiff.
Cut the tomatoes in half length wise. Turn them cut side UP, and you'll have no problems.
Sincerely,
9-fingers Joe (formely employed at Wendy's)