The fault is in the accounting system of your supplier.
The way you can solve it is to enter purchase invoice with amounts VAT inclusive. That way you can just enter line total €96,67 and let Manager figure out VAT from this amount.
Another way is to add second line item for 1 cent to adjust total.
Your supplier system is set to rounding down so the problem is on their side.
however you can adjust the amount for 1c by adding line on Purchases invoice when create this invoice for any difference.
just look of ADD-LINE when you create the invoice