What is displayed and what it is rounded to is not the same thing, similar to your example we also have
julia> round(10.1, sigdigits=2)
10.0
where it is correctly rounded to two significant digits, but since the following decimals are zero it is still displayed in standard float format with a single decimal zero to signify that it is a float with an integer value (I guess that is the reason at least).
So if you want to change the way that is shown as a result I guess you have to override the show method for floats.
If you just want to print it in a specific way you could have a look at @printf, see e.g.