The Excel FLOOR function rounds a number down to a given multiple. The multiple to use for rounding is given as the second argument (significance). If the number is already an exact multiple, no rounding occurs. FLOOR works like the MROUND function, but unlike MROUND, which rounds to the nearest multiple, FLOOR always rounds down to the given multiple.
In the example shown, the formula in cell D6 is
This tells Excel to take the value in B6 ($33.39 ) and round it down to the nearest multiple of the value in C6 (5). The result is $30.00, since 30 is nearest multiple of 5 below 33.39. Likewise, in cell D7, we get 30 when rounding down using a multiple of 10.
You can use FLOOR to round prices, times, instrument readings or any other numeric value.