When I tried this in Fox, I got .99 which is the correct standard deviation.
So what is wrong with Excel? The STDEV function is actually an approximation of standard deviation which is designed for speed. For a "precise" version use STDEVP.

If you have some free time here is the math:

First calculate the average:
=4.625

Then for each value subtract the average and square it:
0.390625 = (4-4.625)^2
0.140625
0.390625
1.890625
2.640625
0.140625
1.890625
0.390625

Finally total these values and square root them.