The default setting on the Shift tab in the VSB is to show each hour broken into 15 minute increments.  This allows you to draw your shift on any of those 15 minute increments to start and end it.  


Note:  You can also change the Work Tab Zoom Level which is independent of the zoom level you have set on the Shift tab.




However, you can redraw the calendar canvas by using the View Options Zoom Level feature.  The Zoom level has 4 different options; low, medium, high and max.  


Low - 30 minute increments




Medium - 15 minute increments 



High - 10 minute increments



Max - 5 minute increments




Once you redraw the calendar canvas to the increments you want you can begin creating shifts based on the increments shown.  For example, if you want to create a shift that starts at 3:10 then you must change your zoom level to high in order to do so.