Think about it like this, each fret is just one note higher than the last, when you get to the 5th fret it is the same note as the open string below it, therefore anything after the 5th fret can also be played in the same octave on the string below.

Also remember there is no such thing as a B# (Or flat C, however you like it) or an E#.


So your strings will look like this up to 5th fret:

E - F - F# - G - G# - A
A - A# - B - C - C# - D
D - D# - E - F - F# - G
G - G# - A - A# - B - C

Noticing a pattern?