Convert output to currency format

Question

Guys, I'm having an issue outputting the final value to "c" format on the below. I have a loan calculation function below and I would like the answer displayed as currency?

is there a better way to do the below calculation?

               double interest, pow = 1;
                interest = Convert.ToDouble(label10.Text);
              
                if (interest > 1.0)
                {
                    interest /= 100.0;
                   
                }

                interest /= 12;
                for (int j = 0; j < Convert.ToInt32(label3.Text); j++)
                    pow *= (1 + interest);
      

                label7.Text = Convert.ToString(Math.Round((Convert.ToDouble(newVehOTRLabel2.Text) * pow * interest) / (pow - 1)));