I appreciate all the additional information you provided, @userandrewkhine.

When transferring from SGD to JPY, you can add the exact amount as an exchange rate. However, if the decimal numbers exceed seven (7), QuickBooks automatically round it off. Thus, it will make a difference.

In the meantime, you can submit a feedback request to our product engineers. This will enable our team to understand your concerns better and enhance your experience using QuickBooks.

Here's how:

1. From the Gear icon, select Feedback.
2. Type in your feature suggestions.
3. Click Next to submit.

I'm adding this article that contains information about exchange rates in QuickBooks Online: Learn about exchange rates in QuickBooks Online.

For future reference, here is an article you can read to get answers to the common questions about QuickBooks multi-currency: Multi-currency FAQ.

Don't hesitate to comment below if you need assistance transferring currency in QuickBooks Online. I'm always here to help. Have a great day.