For simplicity's sake, lets say this is during the rule of Augustus. I'm also curious what proportion of each stratum would do certain jobs but understand that that's probably also harder to ascertain.
Well, I'm not really certain that we can apply totalizing notions of social class across the empire, as it was very large and diverse and had many ways of organizing itself. The richest seem to have had a diversified portfolio, involved in agriculture, the urban economy, trade and imperial administration. The poorest were likely poor farmers and urban laborers.
Beyond that it is hard to say. We have, for example, the tombs of very wealthy bakers and cobblers from the city of Rome.