For this purpose, you can divide a rocket into 3 areas:
- Non-pressurized sections (like the section that contains the engines). These are vented, so there's no pressure difference between inside and outside
- Tank sections. These are typically pressurized to a few bar (in the region of 5-10 bar), with a safety factor of 1.2-1.3. So they should be good to about 10 bar of internal pressure. Atmospheric pressure never gets this high, so the outside pressure isn't really a design parameter for the tanks.
- Habitable sections. These are usually pressurized to 1 bar, with a safety factor (1.3, maybe higher?), so you'll run into trouble above ~2.3 bar of external pressure.
The highest external pressure the rocket encounters during its flight is before takeoff, at sea level, at 1 bar (100 kPa).
At max-Q, dynamic pressure is in the region of 30 kPa at an altitude of 10 km, where air pressure is ~25 kPa, so total pressure is 55 kPa.
The largest amount of stress on the rocket occurs in orbit, where the outside is at 0 Pa and the habitat and fuel tanks are still pressurized to their original values.