Paint costs C# one test fail

Question

I have code:
int colors = Convert.ToInt32(Console.ReadLine());
double dcost = 40.00 + (colors * 5.00)+((40.00 + (colors * 5.00))*0.10);
Console.WriteLine(dcost);
dcost = Math.Round(dcost);
Console.WriteLine(dcost);

Before and used only int and tax as double and next Convert.ToInt32 and have the same problem

int colors = Convert.ToInt32(Console.ReadLine());
int costs = 40 + (colors * 5);
double tax = costs * 0.10;
int t = Convert.ToInt32(tax);
int totalCost = costs + t;

Console.WriteLine(totalCost);

I check few numbers and rounding seems to work well :/

Answer 1

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace SoloLearn
{
class Program
{
static void Main(string[] args)
{
double total_cost;
double cost,tax;

int numberOfcolor = int.Parse(Console.ReadLine());

cost=(numberOfcolor*5)+40;

tax=cost/10;

total_cost=Math.Ceiling(tax)+cost;

Console.WriteLine(total_cost);

}
}
}

Answer 2

Oh okey i changed Math.Round on Math.Ceiling and everything is pass, thanks