All tabacchi shops sell tobacco products--cigarettes, cigars, pipes, lighters, etc. They will also have an after hours machine, but unless you carry an Italian I.D. card you won't be able to buy cigarettes from a machine.
But they are so much more, and can be especially useful to the voyager. You can purchase local bus, tram and Metro tickets and museum and tourist site passes, phone cards (international, too), and francobolli (postage stamps). Buying postage stamps in an actual Post Office can be a lesson in tolerance. For a few stamps, get them in the tabacchi. They can even add time/credit to SIM cellphones or even pay their household bills.
You can buy your bus tickets at the tabacchi shops that display the "ATAF" symbol in their window for €1.20 for a 90 minute pass. If you have a cellphone, you can also buy a one time ticket via SMS, just text “ATAF” to the number 4880105 and in a few seconds you will receive an SMS with your valid e-ticket. This is valid for 90 minutes and the only extra cost is for the SMS itself.
You might also find shipping supplies (labels, envelopes, tape), other stationary supplies (some with very nice pens) and even lottery tickets. Candy is common, as are some salty snacks, like chips. Others might have a vending machine for drinks. Greeting cards and post cards can also be found, but the greeting cards are not the best. Newspapers and the odd magazine might be offered by some, but there are other specialty shops for this called either Edicola or Negozio.
In the end, you might see the "T" sign affixed to a much large shop that specializes in other things, like coffee and breakfast pastries, make-up, jewelry or perfumes.
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