VAT submission when using third party invoicing calculation

I am currently using an automated VAT Calculation / Invoicing service that seems to round off VAT on all invoices. As an example for an invoice of £10 the rounded off VAT is by the automation is £1.67, whereas the actual VAT calculation turns out to be £1.66. For the purposes of filing: Are we obliged to use the total sum of all invoice displayed VAT figures? OR Can we simply calculate VAT applicable on the total sales instead? The total sales figure calculation of VAT is definitely more accurate, rather than summing up thousands of mini invoices with rounded off VAT.

Hi DK,

I would recommend using the method which gives the most accurate amount of VAT to pass over to HMRC.
Please see information regarding rounding down amounts on invoices:
17. VAT invoices for particular situations

Thank you.