By default, all size charts have conversion from centimeters to inches (and viceversa), depending on the metric of the values in your table.
When the conversion formula is applied, the final number is rounded to make sure that it looks nice in the size table. Automatic rounding works as follows:
If your data is in centimeters
50 cm / 2.54 = 19.685 inches
With the automatic rounding, the value is rounded to 0.1. As such
50 cm = 19.70 inches
If your data is in inches
45 inches x 2.54 = 114.3 centimeters
With the automatic rounding, the value is rounded to 0.5. As such
45 inches x 2.54 = 114.5 centimeters
If you are selling jewlery or garnment that requires precision, you may select a custom rounding.