How can a PHP program calculate and round a monthly loan payment?

"Let’s adapt the solution for the loan amortization schedule we developed in Section 4.7.3. First, we’ll read the principle, terms, and interest as command line inputs. Adapting the formula for the monthly payment and using the standard math library’s pow() function, we get\n\n$monthlyPayment = ($monthlyInterestRate * $principle) /\n\n(1 - pow( (1 + $monthlyInterestRate), -$n));\n\nThe monthly payment may come out to be a fraction of a cent, say $43.871. For accuracy, we need to ensure that all of the figures for currency are rounded to the nearest cent. The standard math library does have a round() function, but it only rounds to the nearest whole number, not the nearest 100th. However, we can adapt the “off-the-shelf” solution to fit our needs. If we take the number, multiply it by 100, we get 4387.1 which we can now round to the nearest whole number, giving us 4387. We can then divide by 100 to get a number that has been rounded to the nearest 100th!\n\n$monthlyPayment = round($monthlyPayment * 100) / 100;\n\nWe can use the same trick to round the monthly interest payment and any other number expected to be whole cents. To output our numbers, we use printf() and take care to align our columns to make make it look nice. To finish our adaptation, we handle the final month separately to account for an over/under payment due to rounding."