Hi Dongha,
If you want the result to display two digits after the decimal, you can format the cell to contain a number and display two places after the decimal.
If you want the actual result to be rounded to two places after the decimal, wrap the formula in ROUND(formula,2)
Examples:

B2 contains the formula A1/A2 and has the cell formatted to Automatic with Decimals also left at Auto,
The result is displayed to 15 digit precision, with 13 of those digits after the decimal.
C2 contains the same formula, and produces the same reslt, but the cell is formatted as shown in the Inspector panel to the right.
D2 contains the same formula, wrapped in ROUND: ROUND(A1/A2,2). The value displayed is the same as displayed in C2, but in this cell, that is the actual result of the modified formula.
C4 and D4 contain the same simple formula:
C4: C2*5 D4: D2*5
Each formula works with the actual value in the cell two rows above it, and presents the result with the same formatting as in that cell. Note the difference in results due to the difference in actual value in 2 and D2.
Either rounding method will work for the displayed value. Which applies to your situation depends on what you are doing with the results of the initial division in row 2. If you will use those values in further calculations, you'll need to decide whether the actual value or the rounded value is appropriate to that calculation.
Regards,
Barry