A Norwegian krone is divided into 100 øre, so it is in other words analogous to cents in Euro or Dollar. Øresavregning as I understand it is when you round off the øre, either up or down depending on how many øre it is and what it is to be rounded off to (i. e. nearest whole krone, or nearest 50 øre, etc).

Øreavrunding is another term for the same thing.

--------------------------------------------------
Note added at 42 mins (2013-06-24 09:17:49 GMT)
--------------------------------------------------

Or rounding off of øre, would probably be more correct.

--------------------------------------------------
Note added at 4 hrs (2013-06-24 12:52:45 GMT)
--------------------------------------------------

Happy to be of use!