Contribution total on a contact's contributions tab is 0

This issue was happening for me with 4.2.1 so I upgraded to 4.2.6 in the hope that it would fix it, but the issue remains.

I've a donation contribution page that accepts transactions in EUR via Realex. The donation process works fine and the donation is recorded against the contact in CiviCRM. However, the total amount value is set to 0.00 in the list of contributions for that contact. When I drill into an individual contribution, I can see that the total amount there is also 0.00, but the net amount is set correctly. I don't have any fees, so that is 0.00 as expected. From looking in the database, I see the total_amount column is 0 for that transaction. This happens regardless of whether I choose an amount from the radio buttons or enter one in the "other amount" box.