Start with the evidence
Group source amounts by currency before making a summary. If a common-currency view is needed, show the separate conversion basis rather than silently adding the digits.
Work through the example
USD100 plus EUR100 is not simply USD200. The first useful summary shows USD100 and EUR100 separately until an appropriate, explicitly labelled conversion is applied.
Make the next step clear
Check headings and chart labels for currency clarity. Keep the original group totals available so a reviewer can distinguish the source records from any later reporting calculation.
Keep the source context
All exchange rates in these worked examples are fictional arithmetic inputs, not current market rates. A business must use the source, date and method appropriate to its own review and approved accounting process. Keep original currency amounts available throughout.