Rounding of values then using in another equation

If I input a value in a cell that is to 2 decimal points but only want it to show to one decimal point, I have been using the reduce decimal button. My problem is that if I use that cell in another calculation it uses the raw data to 2 decimal places instead of the rounded or one decimal place.
e.g. 10.43 rounded to 10.4 but the formula uses 10.43 instead of 10.4 in the calculation so the answer is different. What method can I use to get the calculation to use the rounded number instead of the raw number.

Formatting does not affect the underlying cell value.

In the equation that generates the original result, use the ROUND function to get the precision you wish.