Hi, @Stacey52. I'll share an insight on your query to help you fix this issue with your QuickBooks Online rounding up.
Since your pension contribution and nest account don't match due to QuickBooks rounding up, you'll want to check your amounts. Thus, rounded numbers can cause discrepancies in some calculations.
Also, QuickBooks Online automatically rounds up the amount since it will be based on flat-rate amounts when calculating. You'll want to ensure that the pension rates are accurate.
Alternatively, feel free to contact our QuickBooks Online Payroll Support team in case you need help with the pension amounts.
Please see these articles for more details about workplace pensions:
Keep me posted if you still have questions or concerns about tax calculations in QBO Payroll. I'll be around for you. Have a great day!