C# 四捨五入之無條件進位 0.5

public double halfRound(double val)     
{         
double ten = val * 10;         
double key = ten % 10;         

if( key>=5 || key==0 )             
return Math.Round( val, MidpointRounding.AwayFromZero);         
else             
return Math.Round(val, MidpointRounding.AwayFromZero)+0.5;     
}

這樣子就達成目的了！

halfRound(1.2) => 1.5
halfRound(1.6) => 2