Tipping

Don't is the short answer.

Tour guides: no, if you're paying some amount per person already. Yes, 10-20 euros pp if it's a "free walking tour" and the guide is good.
Restaurants: maybe one or two euros, especially if a mom and pop trattoria sort of place, but usually not
Personal car transfers: I usually tip one or two euros per person, esp if the driver handles a bunch of luggage.
Taxis: no. Unless driver is especially super helpful - like really rushes to get you to a train you are about to miss

Here's Rick's advice tipping in Europe. Links from the menu on the left of this page, under Travel Tips.

Italy is not a tipping culture because wages are higher than for their counterparts among the usual tip recipients in the USA. That said, some businesses (some taxis and touristy restaurants, in particular) have learned that they can pressure Americans into giving a tip. Would you tip your dentist or your banker? No? That's how Italians feel about tipping.

Thanks for the insight!!

Tipping mom&pop that own the restaurant and the (numbered!) selling permit, taxi drivers that own a 60,000 € worth cab license and drivers that own the car is just ridiculous.

First of all, please... please... do not tip the guides of free tours. This way you make things easier for employers that do not pay guides or that give them a few cents under the table. I know young history art students who are forced to work without any insurance because "I'll let you ask and keep all the tips from the Americans".

Forcing the US habits into a non tipping culture creates double standards, tourist traps and workers who are allowed to cheat on taxes and enjoy free health care, free education and citizens' basic income.

Perhaps I'm forcing my "culture" on others, but I usually tip taxi drivers in Italy - and also in Spain and England. But my tipping is fairly limited. If the fare is €9,40 (or British equivalent), then I'll give a €10 note and not wait for change. Same if the fare is €9,90. It's a bit trickier if its €10,10, but I'd give €11. This may upset the locals, but I think hanging around for a few generally worthless coins is a bit rude and what taxes they pay is none of my business.

All the websites I looked at say don’t tip at all in Italy.

As Dario wrote, "no tipping." My Italian friends also say the same. It is not typical. The more "touristy" restaurants may expect it from Americans because they know...

I cannot imagine taking one of the commercial "free" tours and not giving a competent guide a decent tip. Rick has reported that the guides have to turn over a substantial amount of money per head to the company. I think it was about 3.50 per person but don't remember whether that was US dollars or euros. So if tour members don't tip, the guide goes deeply in the hole. My standard tip is 10-15 euros for a 90- to 120-minute tour.

If you have a problem with that business model (I hate it; I take other walking tours if I can), the answer is not to take the tour, not to stiff the guide.