C#-Code

using System;
using System.Linq;
					
public class Program
{
	public static void Main()
	{
		double[] _in = {7.1, 8.4, -2.4, -2.6, -8.3};
		double[] _out = _in.Select(x => round(x, 5)).ToArray();
		
		for(int i = 0; i < _in.Length; i++){
			Console.WriteLine("{0} => {1}", _in[i], _out[i]);
		}
	}
	
	private static int round(int val, int factor){
		return (int)(Math.Round((double)val / (double)factor, 0) * factor);
	}
	
	private static float round(float val, float factor){
		return (float)(Math.Round((double)val / (double)factor, 0) * factor);
	}
	
	private static double round(double val, double factor){
		return Math.Round(val / factor, 0) * factor;
	}
	
	private static decimal round(decimal val, decimal factor){
		return Math.Round(val / factor, 0) * factor;
	}
}