Event participant amount and contribution amount with non-default decimal separator is wrong

When you select a non-default decimal separator calculations of the event price and contribution amount gets messed up.

Steps to reproduce on demo site.
Set decimal operator to ',' and thousand seperator to '.'
Create priceset with a field with a decimal amount.
Create event to use this priceset, and enable pay later.
Register person for this event with the priceset. Make sure amount which has to be paid is a decimal amount. Register payment as wel.

You'll see now that on the participant info the amount is not correct. On the created contribution the amount is also not correct, and even different of the participant amount.
This problem doesn't occur with '.' as decimal separator.