using System;

public class Program

{

    public static void Main()

    {

        decimal[] vatAmountLines = {(decimal)20.17, (decimal)20.175, (decimal)20.18};

        decimal headerCorrection = (decimal)0.05;

        decimal vatAmountRecov;

        decimal vatAmountNonR;

        decimal roundingDiff;

        decimal vatReclaimPerc = (decimal)0.5;

        foreach(var vatAmountLine in vatAmountLines){

            vatAmountRecov = Math.Round((vatAmountLine - headerCorrection) * vatReclaimPerc, 2, MidpointRounding.AwayFromZero);

            vatAmountNonR = Math.Round((vatAmountLine - headerCorrection) * (1 - vatReclaimPerc), 2, MidpointRounding.AwayFromZero);

            roundingDiff = Math.Round(vatAmountLine, 2, MidpointRounding.AwayFromZero) - headerCorrection - (vatAmountRecov + vatAmountNonR);

            Console.WriteLine($"\nValue: {vatAmountLine}");

            Console.WriteLine($"\nHeader corrected values:");

            Console.WriteLine($"\t{vatAmountRecov}, {vatAmountNonR}, {roundingDiff}");

​

            vatAmountRecov = Math.Round(vatAmountLine * vatReclaimPerc, 2, MidpointRounding.AwayFromZero);

            vatAmountNonR = Math.Round(vatAmountLine * (1 - vatReclaimPerc), 2, MidpointRounding.AwayFromZero);

            roundingDiff = Math.Round(vatAmountLine, 2, MidpointRounding.AwayFromZero) - (vatAmountRecov + vatAmountNonR);

​

            Console.WriteLine($"Values:");

            Console.WriteLine($"\t{vatAmountRecov}, {vatAmountNonR}, {roundingDiff}");

            Console.WriteLine("\n========================================================================");

        }

    }

}