I would not recommend Rodinal for 35mm Tri-X unless your trying for a certain effect and wish for grain. Your development time is about 2.5 min longer than the charted suggestion of 10 min at 20c. If you are scanning film the combination is bad. On the other hand Ralph Gibson http://www.ralphgibson.com/ uses Rodinal with 35mm. His images are contrasty and often show some grain.
The link above mentions how Rodinal depresses middle values. Mike Johnston makes an important point how the Film/Developer/Paper (FDP) combination is linked to the final image.
The previous poster mentioned film developers which improve sharpness and mid tone values vs Rodinal. Another is Xtol diluted up to 1:3. It is sharp but not in the same class as his suggestions. Development time for Tri-X 135, EI 400, 20C is 12.50. You can shoot at EI 200 without adjusting the time if easy on agitation. Xtol at 1:2 is the dilution I typically use. Time at 20c is 10.5.
If you develop with Xtol or D-76 it's recommended to use 500ml per roll of undiluted stock chemical when developing at 1:1 dilution or higher. That recommendation includes Rodinal but I confess to using 7.5cc of stock Rodinal with 17 oz of water.
I like Xtol but 5L is more stock developer than I use in 12 months.