Почти решена Trade commissions

string sity = Console.ReadLine();
double sales = double.Parse(Console.ReadLine());

double comision = 0;
if (sity == "Sofia")
{
    if (sales >= 0 && sales <= 500)
    {
        comision = sales * 0.05;
    }
    else if (sales > 500 && sales <= 1000)
    {
        comision = sales * 0.07;
    }
    else if (sales > 1000 && sales <= 10000)
    {
        comision = sales * 0.08;
    }
    else if (sales > 10000)
    {
        comision = sales * 0.12;

    }
}

else if (sity == "Varna")
{
    if (sales >= 0 && sales <= 500)
    {
        comision = sales * 0.045;
    }
    else if (sales > 500 && sales <= 1000)
    {
        comision = sales * 0.075;
    }
    else if (sales > 1000 && sales <= 10000)
    {
        comision = sales * 0.1;
    }
    else if (sales > 10000)
    {
        comision = sales * 0.13;

    }
}
else if (sity == "Plovdiv")
{
    if (sales >= 0 && sales <= 500)
    {
        comision = sales * 0.055;
    }
    else if (sales > 500 && sales <= 1000)
    {
        comision = sales * 0.08;
    }
    else if (sales > 1000 && sales <= 10000)
    {
        comision = sales * 0.12;
    }
    else if (sales > 10000)
    {
        comision = sales * 1.45;

    }

}
if (sales < 0)

{
    Console.WriteLine("error");

}
else
{
    Console.WriteLine($"{comision:f2}");
}