Hi there MCH-,
It's important for your transactions to be entered correctly for your books to balance. QuickBooks Online is a great tool able to help you keep track of sales and expenses to see the profit of your company. I can provide some information about decimals in QuickBooks Online.
In QuickBooks Online., only 2 decimals can be present when entering an amount for a transaction. I can see how having more decimals would be a feature that could help you keep track of transactions involving cryptocurrency. I recommend you leave feedback in the system by clicking on the Gear icon, then Feedback. Comments made in this section are taken into consideration when designing new features for QuickBooks Online.
If you have any other questions, feel free to reach out here,