The 10 cent value was issued in 1858, when it was realized that the three values issued in 1855 were not enough to meet all the new needs that had arisen.
The main postal rates in which it was used were the rate for the first radius to Switzerland, the double-rate charge for circulars, periodicals, or letters within the city, and the military rate, especially interesting on issues from 1858 through 1860.
From 1 January 1861, the single 10 cent value became the ordinary, standard rate, since in some annexed regions of Italy, to encourage the integration of the population with the new Sardinian-Italian government, postal concessions were granted, allowing correspondence to be sent within the Grand Duchy of Tuscany and the Kingdom of Sicily for only 10 centesimi; later, with the arrival of centesimi stamps in the former Neapolitan Provinces, this postal concession was also adopted in those regions.
There are other interesting rates with the c. 10, such as the so-called neighboring-radius rates within the Romagna, the Marche, and between Sardinia and Lombardy-Venetia (before 1859), and so on: all of them are rare to very rare.
Two value tables were prepared for the 10 centesimi; the first includes the printings from 1858 through the first half of 1861, the second includes the printings from the second half of 1861 through 1863.
For further details, we recommend reading the book by Umberto Ballabio, which you can find HERE.
