Price round up / down does not work properly

[DonCarlos]

Hi,

I do not know if this is the right categorie to post this in.

My question is:

I created a custom import that imports products from a XML file.
This all works great but I have a problem rounding the price.

Lets say I have a product A.
The price I pay is: 24.70
The price I sell it for ex TAX: 39.69

I use 19,6 % tax so after the tax it is: 47.47

I want it to be round up to 47.50 but I can't get this to work...
I tryed in the admin panel setting it to inferieur / classic and such but that did not work.
Any help?