Long ago, on our first trip to Rome (and Italy), I fondly remember our introduction to tipping in Italy. We were staying outside the city center, so had to take the subway into town.
At the subway station, we had not eaten all day and there was a small stand selling sundries and sandwiches. We got food and water.
We were also unsure at which direction to take on the subway. The person in the stand spoke no English and we spoke no Italian. He spent considerable time trying to direct us and giving us some guidance when we got to our destination. Lots of gesturing, pointing on maps, etc. It took a bit of time.
Our bill came out to 7.65 euros (I remember). I gave him at 10 euro note. When he gave me change, I slid it all back to him. He waved at me, slid the 2 euro coins back to me and said, "you" and slid the .35 toward himself and said "me".
At the time, we were stunned. It was a great experience.