Upfront costs/revenues are not time-discounted (they are assumed to occur immediately). End of life costs/revenues are time-discounted by the total life span (they are assumed to occur immediately at the asset's end of life). All other time periods are discounted using the assumption that cash flows at the end of the period.
The calculator uses full numerical precision internally, but it rounds all displayed values to three significant digits. This is done for clarity and to reflect the many uncertainties in predicting the future.
Interest rates shown are always annual rates.