Some database systems do rounding differently than would typically be considered. Most people assume that the ROUND() function would round to the nearest whole number.
However, many DBMS's do "Bankers Rounding".
This means that the number being rounded is rounded to the nearest EVEN whole number.
I.E. if the number being rounded was 11.3, the logical rounding to most people would be to 11. However, since 11 is odd, "Bankers Rounding" would round this number to 12 instead.