Cannot figure out why loop isn't getting the correct sum

I'm trying to make a mortgage calculator, and for whatever reason it's getting the wrong sum for the principal and the interest. Is it possible that because it's being added up inside of the do-while loop that it gets it wrong? When I run the program it comes up with 8233.68 for the principal and 11423.59 for interest. If you sum them up on a calculator, it should be 8209.30 for principal and 11447.97 for the interest.

double termSelection = 0.0359;
double principal = 325000;
double effectiveMonthlyRate = 0.0029695338579054376;  
double monthlyPayment = 1638.1053796234314;
double monthlyInterest = (principal * effectiveMonthlyRate);
double monthlyPrincipal = (monthlyPayment - monthlyInterest);
double closingBalance = (principal - monthlyPrincipal);
int month = 1;
double totalPrincipal = 0;
double totalInterest = 0;
termSelection *= 100;
//monthly payment schedule header
System.out.println("");
System.out.printf("%nInterest Rate: %.2f%%", termSelection);
System.out.printf("%n%53s", "Monthly Payment Schedule");
termSelection /= 100;
//monhtly payment schedule body
System.out.printf("%n%5s%14s%15s%15s%15s%15s", "Month", "Open Bal", "Payment", "Princ", "Interest", "Closing Bal");
do{
System.out.printf("%n%5s%14.2f%15.2f%15.2f%15.2f%15.2f", month, principal, monthlyPayment, monthlyPrincipal, monthlyInterest, closingBalance);
month++;
principal = closingBalance;
monthlyInterest = principal * effectiveMonthlyRate; 
monthlyPrincipal = monthlyPayment - monthlyInterest;
closingBalance = principal - monthlyPrincipal;
totalPrincipal = totalPrincipal + monthlyPrincipal;
totalInterest = totalInterest + monthlyInterest;
}
while (month <= 12); 
System.out.println("");
for (int count = 0; count <= 80; count++){
System.out.print('=');
}
System.out.printf("%n%5s%44.2f%15.2f", "Ttls", totalPrincipal, totalInterest);

The problem is that you are doing calculation before you even enter the loop

double closingBalance = (principal - monthlyPrincipal);

should be

double closingBalance = (principal);

output

 Ttls                                     8209.30       11447.97

You recalculate initial values of monthlyInterest and monthlyPrincipal on first iteration of the loop and then add them to totals. Add them to totals first and then recalculate.

    do {
System.out.printf("%n%5s%14.2f%15.2f%15.2f%15.2f%15.2f", month, principal, monthlyPayment, monthlyPrincipal, monthlyInterest, closingBalance);
principal = closingBalance;
totalPrincipal += monthlyPrincipal;
totalInterest += monthlyInterest;
monthlyInterest = principal * effectiveMonthlyRate;
monthlyPrincipal = monthlyPayment - monthlyInterest;
closingBalance = principal - monthlyPrincipal;
month++;
} while (month <= 12);