I'm thinking child profiles versus parent, like for TV shows.  Do we round the individual episodes for the child profiles and then sum them or do we sum exact times and then round at the end?  Additionally, do we sum all the rounded child profiles to derive the parent number or do we go with exact numbers for all the episodes and then round at the end?

I keep an excel file all set up for this purpose, I just type in the runtimes of the episodes (or play-all option), and then various bits in the template tell me the runtimes for each disc and the set as a whole. Then I just copy the disc/set times to a separate sheet for keeping, just in case.

Quoting Nadja:

Quote:
I keep an excel file all set up for this purpose, ...

Same thing here excel:
add all the times in one column in time format, make a sum of that time format
of the sum field make a minute  rounded conversion:
=Hour(A5)*60+MINUTE(A5)+Round(SECOND(A5)/60;0) (where A5 is the reference to the sum in time format)
- every hour 60 minutes
- get remaining minutes
- get the seconds, convert to minute (/60), convert below or above 30 seconds to minute above or below.
this gives you the minute running time for each child disc.
then you could make a column totaling all minutes/child disc what would give you the Box running time in minutes
then you could make a third column totaling all minutes/boxes for grandfather box

If you have excel: this is the file:
children run time to box to total boxes
it is made in excel 2000 (dutch), but it should run on english versions)

looks like it does not run in English.
If you don't get a result in A5 the formula =SOM(A1:A4) should change to
=SUM(A1:A4)

in B5 you find the formula
=UUR(A5)*60+MINUUT(A5)+AFRONDEN(SECONDE(A5)/60;0)
replace the function names:
UUR = Hour
MINUUT = Minute
AFRONDEN= Round
SECONDE= Second

so the formula should look like this, copy and paste line in to B5
=Hour(A5)*60+Minute(A5)+Round(Second(A5)/60;0)

if it still not works it could be the delimiter ; change that to ,
copy this one in to B5 and it should work:
=Hour(A5)*60+Minute(A5)+Round(Second(A5)/60,0)

usage enter episode running time in a1-a4 Cell A5 should give you the total time. B5 should give you the time in minutes. The result of B5 copy this to c1 for first dvd, c2 for second dvd , ..., C7 for dvd seven. C8 gives you total time in minutes for the Box. If you have collection box with boxes of DVD's (grandfather profile). You can take the result for DVD box 1 in C10, DVD box 2 in C11, ..., DVD Box 10 in C19. The result in C20 would be total running time for the box with dvd boxes.

indeed, why don't you put your collection on paper