Displaying average time in [MM:SS] format

I have a column storing call duration in minutes and fractional minutes (example: 4 min and 30 seconds is stored as 4.5)

• I'm calculating the average monthly call duration and displaying it in chart below.
• After calculating the average, I'm using DAX to convert values to time interval

                  Dec --> MM:SS

                  5.87  --> 05:52

                  5.92  --> 05:55

                  6.02  --> 06:01

                  5.89  --> 05:54

My challenge is to show the lables above each column in time interval notation [MM:SS] as opposed to fractional minutes.

Any ideas greatly apreciated.