A building contractor receives a construction loan totalling $2,000,000 and receives $1,000,000 immediately in three instalments, and then $500,000 every six months with interest at 15% semiannual conversion rate until the end of the second year. Starting at the end of the second year, all accumulated principal and interest are treated at a 30-year mortgage with a nominal interest rate of 12%. The known loan repayment method is; Monthly payments for the first five years are half of those for the subsequent years. Calculate the amount of the 12th repayment.