A few minutes ago I wrote a rounding function for myself in C. Probably not the best implementation, but it works all right. If you’re interested, check it out (I’ve put some sample values in the comments):

int iroundf(float value)
{
    if(value > 0.0)
    {        
        int unsigned cutvalue = (unsigned int)value; // 3.8234234 => 3
        float remain = value - cutvalue; // 3.8234234-3 = 0.8234234
        
        if(remain >= 0.5) // 0.8234234 >= 0.5 => TRUE 
            return cutvalue + 1; // iroundf(3.8234234) => 4
        else
            return cutvalue;
    }
    
    if(value < 0.0)
    {
        int cutvalue = (int)value; // -1.34 => -1 // -4.67 => -4
        float remain = value - cutvalue; // -1.34-(-1) = -0.34 // -4.64-(-4) = -0.64
        
        if(remain >= -0.5) // -0.31 >= -0.5 => TRUE // -0.61 >= -0.5 => FALSE
            return cutvalue; // iroundf(-1.34) => -1
        else
            return cutvalue - 1; // iroundf(-4.67) => -5
    }
    
    return 0;
}

update: I just came across the following very short and elegant solution (talk about forests and trees…)

int result = (int)(float_number + 0.5);