Funny thing, I was just reading my Foder's book on Rome today. What I found regarding bathrooms was interesting.
Toilets - men/women - gabinetti- uomini/donne
" You will find public toilets at railway stations and in larger museums, but otherwise they are few and far between. There are toilets in Piazza San Pietro, either side of the square, and others at the Colosseo."
"In other parts of Rome you will need to use the toilet in a bar or cafe. Although, they are obliged to let you use their facilities, staff prefer you to buy something."
"Facilities can be basic, to say the least. Toilet paper may or may not be provided, and sometimes there is only one toilet for both men and women. In some places there will be a dish for gratuities - you should tip around 25 c. Where separate facilities exist, make sure you recognize the difference between signori (men) and signore (women)."
PS I always carry a small travel size roll of TP with me when I travel outside of the country and keep a roll in my car at home.