since I updated my site to 1.9, every order that is paid with Paypal is shown with the "suspected fraud"-tag. I've seen multiple topics with the same problem. But as far as I've seen, this is mostly due to conversion rates. The problem with my site is that I don't offer multi-currency. Everything is in Euro. The total also differs from the received money by a few cents (here's an example: https://imgur.com/ridmzuo).
Any idea what is going on here?
The suspected fraud tag can come when the total that you're sending to PayPal doesn't quite add up. Normally, as you say, this is due to multi-currency problems.
What's your tax configurations, is Magento showing any warnings about the potential for incorrect calculations with your current configuration? If your PayPal account a euro account?
Magento isn't showing any warning. Yes my PayPal account is a Euro account.
I have one tax rule with a tax rate of 20% which is the default product tax class.
Everything worked fine before the update and it's only affecting PayPal orders now. The total sums from orders with bank transfer payment selected are correct. But when a customer selects PayPal the total sum is always lower by a few cents. I've also tried to calculate the difference to see if there is a specific amount or percentage that is deducted from the total sum, but there isn't. It's completely random.
It's a bit out of date but this blog post might be useful but it's only a workaround. https://www.hummingbirduk.com/suspected-fraud-transactions-magento/