Compute Sales Tax - Please help

fpielhau

I have a photo store that I purchased and have been making some changes. The software did not come with adding sales tax to the shopping cart. So I am building it. Here is what I get:

The total cost from the cart is $15.00

Sub Total: $15.00
Tax: (5.5%) $0.83 (This is the correct tax charge which is .825 it rounds up ok)
Shipping Free: $0.00
Total: $15.82 (This is not correct it doesn't round the tax up to .83)

My Code: (With comments)

											<?

												$total = $total + $price; [COLOR=Black]// ---- $total = $15.00[/COLOR]
												$tax = $total * .055; [COLOR=Black]//------ Tax is .825[/COLOR]


												}
											?>
											<? if($cart_rows > 0){ ?>
											<tr>
												<td align="right">
													<table>
														<?php


															if($shipping){
																echo "<tr><td><span><b>Sub Total: </td><td><font color=\"#ff0000\">" . $currency->sign . dollar2($total) . "</font></b></span></td></tr>";

//---This discplays the correct tax amount while rounding up
echo "<tr><td>Tax: (5.5%)</td><td> " . $currency->sign . dollar2($tax) . "</td></tr>";

																echo "<tr><td><span><b>Shipping: </td><td> <font color=\"#ff0000\">" . $currency->sign . dollar2($shipping) . "</font></b></span></td></tr>";


												[COLOR=Black]//---This is where it computes the tax but doesn't round up.[/COLOR]											
	$total+= $tax;
																$total+= $shipping;
															} else {
																echo "<tr><td><span><b>Sub Total: </td><td><font color=\"#ff0000\">" . $currency->sign . dollar2($total) . "</font></b></span></td></tr>";

//---This discplays the correct tax amount while rounding up echo "<tr><td>Tax: (5.5%)</td><td> " . $currency->sign . dollar2($tax) . "</td></tr>";

																echo "<tr><td><span><b>Shipping Free: </td><td> <font color=\"#ff0000\">" . $currency->sign . dollar2($shipping) . "</font></b></span></td></tr>";


							[COLOR=Black]//---This is where it computes the tax but doesn't round up.[/COLOR]	
							$total+= $tax;
																$total+= $shipping;
	}

?>[/COLOR]
Please help...

Thanks in advance....

gardnc

Try $tax = round($total * .055,2);

fpielhau

Thank you for the quick reply.

Ludichrist

You're eventually going to run into trouble working with floats like this. You'll find sooner or later that you're missing a penny somwhere.

I suggest that you convert your values to integers before doing math on them.

$price = (int) ($price * 100 + .5);

There isn't a quick way to explain why, but it has to do with the way processors work with floating point numbers.