I am really scratching my head, but it seems like this is not possible in Google Spreadsheets. I want to format a number cell in kroner without any decimals. All I get is "kr 38,434.00" I want this number without any decimals. Could it really be that this is not possible.
In Google New Sheets - being rolled out in April 2014, setting currencies and decimals are split, as you can set the currency first (now hidden at Format -> Number -> More Formats -> More currencies) and then use the Decrease/Increase buttons to change the decimals:
Note that I found a bug in that if you decrease decimals on multiple cells, then they will all be reset to the currency of the first cell - so select each currency on its own.
It is not as of 2014-04 possible to 'upgrade' existing sheets to the 'New sheets' as far as I know.