What is the correct way to calculate and round variables in PHP?

When calculating and rounding variables in PHP, it's important to use the appropriate functions to ensure accurate results. To calculate a value and round it to a specific number of decimal places, you can use the `round()` function. This function takes two parameters - the value to be rounded and the number of decimal places to round to. Additionally, you can use `number_format()` to format a number with grouped thousands and a specified number of decimal places.

// Calculate a value and round it to 2 decimal places
$value = 12.3456;
$roundedValue = round($value, 2);
echo $roundedValue; // Output: 12.35

// Format a number with grouped thousands and 2 decimal places
$number = 1234567.89;
$formattedNumber = number_format($number, 2);
echo $formattedNumber; // Output: 1,234,567.89