50 euro cents for the first minute is a good rate; there are plans with better rates, but they sometimes require sign up fees. I use Wind, it has the same 50 cent rate, but with taxes the first minute is more like 65 cents. If you sign up for their "call your country" plan when you buy the sim card it's 35 cents/minute. Wind has a phone card for 5 euro, you can use it with their prepaid sim and not have any charges against your sim- it drops the cost considerably. You might be able to use that card or other brands of phone cards with other sim cards, you'll have to study the fine print. I'm sure the other cell companies have similar cards. Those cards are a bit of a PITA to use, (but they do have voice instructions in english) but they save a lot of money. You can buy them at a tobacco store. With that system you can get a sim with the minimum funds on it, and use the phone card.

The tobacco stores sell dozens of other phone cards, each one has different rules and fees- caveat emptor.

Wind is much less used than Tim and Vodafone are much more widely used. I don't know which one will get better signals in Rome; all of them get spotty in the cities, since some of the solid old buildings can block the signals.