is it ok to pinch one's nose when sneezing?

You should not forcibly stifle a sneeze. As you say, it can do damage to the ears because of the connection between the inner ear and the nose. The best way to deal with a sneeze is to place the finger UNDER the nose and to push up on the cartilage at the base of the nose. This generally relieves the urge to sneeze completely. It is a trick worth knowing, especially when driving. A sneeze can disable one's awareness for 2 to 3 seconds or more. At 60 miles per hour, your car will have travelled nearly 100 yards with you virtually blind.