Use decimal, not double, otherwise you’re not starting with the exact values you think you are, and you get the expected results.
9.05 ===> 9.1
9.15 ===> 9.2
9.25 ===> 9.3
9.35 ===> 9.4
9.45 ===> 9.5
9.55 ===> 9.6
9.65 ===> 9.7
9.75 ===> 9.8
9.85 ===> 9.9
9.95 ===> 10.0
With doubles, most of the values are slightly off from the decimal literals in the code, and so are rounded to the nearest number. Only two are actually at the midpoint, and are rounded to even in .NET Core. But as @Traveller points out this isn’t general rounding behavior; it’s specific to how floating point numbers are printed.
9.05000000000000071E+000 ===> 9.1 <- rounded to nearest
9.15000000000000036E+000 ===> 9.2 <- rounded to nearest
9.25000000000000000E+000 ===> 9.2 <- rounded to even
9.34999999999999964E+000 ===> 9.3 <- rounded to nearest
9.44999999999999929E+000 ===> 9.4 <- rounded to nearest
9.55000000000000071E+000 ===> 9.6 <- rounded to nearest
9.65000000000000036E+000 ===> 9.7 <- rounded to nearest
9.75000000000000000E+000 ===> 9.8 <- rounded to even
9.84999999999999964E+000 ===> 9.8 <- rounded to nearest
9.94999999999999929E+000 ===> 9.9 <- rounded to nearest