One way:

Enter 8:00 in A1. Enter 8:05 in A2. Select A1 & A2. Grab the fill handle
(lower right corner of the selection) and drag down as far as required.

alternatively,

Enter 8:00 in A1. Select the desired range. Choose Edit/Fill/Series...

Choose Type:Linear. Enter 0:05 in the Step field. Click OK.


In article ,
"IUnknown" wrote:

Trying to do a series using 5 minute increments (08:00, 08:05, 08:10, etc.).
Only options by date are day, wekday, month, and year.