I know that the nth term of a geometric series is
$$f(n, a_1) = a_n = a_1 r^{n-1}$$
In my case however, since I am dealing with money, I am rounding each term to two decimal places. I calculate the nth term using the previous term like so
$$ g(n, a_{n-1}) = a_n = round(a_{n-1}r) $$ where $$ a_1 = 1000; r = 1.000833333 $$
As you can see below, using $f$ will produce a discrepancy. For example, see below how rounding $f(2)$ will produce 1001.67 rather than 1001.66
n f() g()
1 1000.833333 1000.83
2 1001.667361 1001.66
What is the formula to calculate the nth term of this geometric series where each term is rounded to two decimal places?