I don't have small change / coins.
'Spiccioli' — SPIC-cho-li. Three syllables. The 'cc' gives a sharp 'ch' sound.
Say this when you only have large notes and need to pay cash. Helps the cashier understand you cannot give exact change and alerts them to prepare to make change for you.
'Spiccioli' = coins or small change. 'Non ho spiccioli' = I don't have coins. 'Spiccioli' can also refer to any small change (centesimi coins). The word is informal and colloquial — the formal equivalent is 'monete' (coins) or 'resto esatto' (exact change).
Ho solo un biglietto grande.
I only have a large note.
Explains the denominations you have.
Riesce a cambiarmi?
Can you give me change?
Asks for change directly.
Ha qualche spicciolo?
Do you have any small change?
Asks the cashier if they have coins.
Italians have a love-hate relationship with coins. The 1 and 2 cent coins are technically legal tender but many Italians discard them or round to the nearest 5 cents ('arrotondamento'). However, shops are required to accept them by law.