On sale receipts there’s a capital letter after the price of each sold item (mostly an ‘A’). This capital letter indicates the VAT rate that has been applied to this particular position.
Also, each sales receipt has a VAT declaration section: It’s further down, right underneath the payment method(s).
There any applied VAT rate is broken down into percentage, VAT amount and net total - and a capital letter as well.
In those cases where more than one different VAT rate is applied, those capital letters indicate the applied VAT rate per item: If there’s an ‘A’ behind the price of an item, VAT rate ‘A’ is applied; if there’s a ‘B’ behind the price of an item, VAT rate ‘B’ is applied and so on.