Here are some step-by-step calculations so you can see fairly clearly what's going on:-

The [effective annual interest rate](http://en.wikipedia.org/wiki/Effective_interest_rate#Calculation) is given by

    ear = (1 + i/n)^n - 1

where `i` is the nominal interest rate and `n` is the number of compounding periods.

    ear = (1 + 0.1/12)^12 - 1 = 0.104713 = 10.4713 %

The [monthly rate](http://en.wikipedia.org/wiki/Nominal_interest_rate#Monthly_compounding) is

    r = (ear + 1)^(1/n) - 1 = 0.00833333 = 0.833333 %

The [monthly repayment](http://www.financeformulas.net/Loan_Payment_Formula.html) is given by the formula

    p = r*pv/(1 - (1 + r)^-n)

where `pv` is the present value of the loan

    p = 0.00833333*1000/(1 - (1 + 0.00833333)^-12) = 87.9159

This gives a total repayment of `p*12 = 1054.99`

You might have expected the loan to cost `(1 + ear)*pv = (1 + 0.104713)*1000 = 1104.71` but the repayments progressively reduce the amount owed so the total repayment is only 1054.99.