create a separate table like this

0....... .5
.5.......1.0
1.0......1.5
1.5......2.0

etc, call it table

Now in a spare column next to your data in column A

=vlookup(A1,table,2)

this will give you your bin numbers

Now create a pivot table to count how many in each bin, and use this to draw the histogram.
note that 0.499999 will return 0.5
0.500000 will return 1.0

if you wanted to include 0.5 in the 0 / 0.5 group, you would make the left hand column of table read

0.0
0.50000000001
1.00000000001
1.50000000001

etc