JIRA timelogs rounds up the Worked Hours on a ticket, is different to the maths that Tempo uses to round up the Billed Hours.
What I have noticed, and tested is:
A timelog for 13mins is created - and input on the worklog as 13m
Converting this to decimal, it is displayed as 0.22, but it is actually 0.216666666666666667
Logging 13m and 3h 13m shows 3.44 in the worked and 3.43 in the billed
If I were to directly input the timelogs in decimal, as 0.22 and 3.22, they add up to the same 3.44 in both
The way the worklogs function, all time is input in h/m - even when creating a new worklog, If I were to input it in as 0,22, it converts is to 13m in the display.