I've never heard it called "Swedish Rounding" - it sounds very interesting...!
Is that like a "spanish practice" or a "French letter"?
I think we're on the same page here; if the flight time comes out as 1hr 12minutes, it goes in the log as 1hr 10minutes. If it comes out as 1hr 13minutes, it goes in the book as 1hr 15minutes.
If you're working in decimal, I can't help!