gratuities and tips:

in Italy and generally in Europe tips and gratuities are always very welcome. It is not a must though and not expected. They are given as appreciation for a job well done with minor exceptions... all staff receive a decent fixed salary and usually tips are not individual, but are divided amongst all staff at the end of the evening (restaurants and bars).

in a coffee bar, when ordering coffee at the bar, you stand a better chance of being served quickly and well, if together with the payslip you add 10 cents. The barman sees the coin and will be more attentive to your needs. Well, that is the theory at least...

in a restaurant unless a service charge is included in the bill, it is OK to leave 8/10% tip of the total. The higher the total bill the lower the percentage.
For example: the waitress was friendly and attentive. You didn't have to wait excessively for your lunch and the bill was 27 euro for two. You could pay 30 euro and leave 3 euro tip.
If it was a group and the bill was 500 euro, a decent tip would range between 20/25 euro. No need to leave 10% in this case as 50 euro would really be too much.
In a taxi a tip isn't really expected. All drivers own their own car and work for themselves. A tip is OK, if it is easier with the change and usually would not be more than 1 or 2 euro.

any CIMT staff on tour with you, apart from Francesco (the owner), would love one ... ; ) ... nothing much, but an appreciation of a job well done is always good.