What potential issues or errors could arise when implementing the weight-dependent shipping module in PHP?

One potential issue that could arise when implementing the weight-dependent shipping module in PHP is incorrect calculation of shipping costs due to rounding errors. To solve this issue, it is important to ensure that all weight calculations are done using precise numeric data types, such as floats, and to round the final shipping cost to the appropriate number of decimal places.

// Ensure weight calculations are done using floats
$weight = 10.5;

// Perform shipping cost calculation
$shipping_cost = $weight * 0.5;

// Round the final shipping cost to 2 decimal places
$shipping_cost = round($shipping_cost, 2);

echo "Shipping cost: $" . $shipping_cost;