Place one cube in each of the 4 bottom corners and a fifth at the bottom center rotated 45º. A second layer of 5 can sit on top of these.
The smallest box that can be filled the way would have edge length 6+1.5√2≈8.1213
And if the box need not be a cube the height could be merely 6.
Posted by Jer
on 2014-05-29 15:18:16