Most large corporations on America have personnel policies these days that mandate tolerance of sexual minorities and transgender people. With smaller companies it may be more hit and miss. There seems to be little difficulty with internal occupations like IT and accounting where the employee never meets customers. I'm not so sure about sales and retail situation, though. While those positions should be more accessible to TG people, I know companies are the most touchy about the appearance of their reps.
Generally, though, you always want to look your best and come across to people in a positive way. It's no doubt that TG people have to try harder, just as genetic women have to try harder in many work situations. The trick is to be so good they can't turn you away.