Magento Credit memo's total must be positive

Question

I have a problem with my Magento installation. There is a order with a discount coupon. The value of the coupon was more then the order total, so the grand total of de invoice should be zero. It's not zero, it's -0,01. I know this is a php rounding problem, but I don't know how to fix this. I've tried the following:

Installing the bcmath extension and tried to fix it like described in: Negative grand total for orders

For me it's no solution.

A screenshot of the problem: http://s15.postimg.org/yhl9rcx2z/totals.png

Hope anyone can help! Thanks!

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UPDATE: I've just changed some records in the sales tables. Now the totals are €0,00. That's good. Now the next problem is there.

In the Items Ordered list there is one product. The Row Total there is still €-0,01. Is this one calculated dynamicly? What can I do to change this one? Also the button for a credit memo has disappeared.

Anybody know's what to do in this situation?

Answer 1

I've deleted the order, couldn't find a solution.

Hopes it never happens again.

Thanks.