Learn Italian: Il caffè costa un euro e venti centesimi. - The coffee costs one euro and twenty cents.

The accent mark shows that the spoken stress falls on that final vowel. In Italian, nouns that end with an accented vowel are invariable, meaning they don't change their ending in the plural. To say "the coffees," you simply change the article and leave the noun alone: i caffè.

If the coffee cost two euros, would I say due euri?

No, you would say due euro. Even though most masculine nouns ending in -o change to -i in the plural, the word euro is an exception. It stays exactly the same whether it is singular or plural.

Can I drop the word centesimi in everyday conversation?

Yes! Just like in English where we might say "one twenty," Italians very often drop the word centesimi and simply say un euro e venti.

What is the singular form of centesimi?

The singular is centesimo (one cent). It is closely related to the word cento (one hundred), literally meaning a hundredth of an euro.