What if the value cannot be accurate to one decimal place?
Thinking about data in terms of decimal places is misleading.  You should really be thinking about data in terms of the precision with which you know the values, also sometimes referred to as significant figures.
How precisely do you actually know those values? It is 12.736% because you actually have enough data to say that it is accurate to one part in 100,000, or is it because of something like Excel defaulting to three decimal places?
You need to figure out the amount of error in your measurements, and once you know that, then the answer to your questions will be clear.