invoice specification of apple.com/bill iTunes.com

Receipts for iTunes purchases are emailed to your Apple ID email account. If you received an email receipt and you did not make a purchase, it is possible the email is a phishing attempt to get your account information. See this, Recognize and avoid phishing messages, phony support calls, and other scams - Apple Support

See this if you found an unfamiliar charge on your bank statement, If you see 'apple.com/bill' or an unfamiliar charge on your statement - Apple Support This also explains how to check your purchases, and how to contact Apple if you have questions.