Parts of smoking are good for you, but, ironically enough, most of those parts that have little to do with the sigarettes themselves.
What parts, you ask? Well, I will tell you.
When working on something all day long (like a job) it's very good to take breaks several times and clear your head. Say, five minutes every hour to take a smoking break. But it doesn't even have to be smoking. Just standing outside the office for five minutes, away from your work, can help immensely. It helps you let go for a moment so you can look at your problems with a fresh view and solve them.
Of course it's important not to overdo it. You're not supposed to have half-hour breaks every hour, no matter how tempting it is to get away from it all.
ps. Just to clarify: I don't smoke and have never smoked.