Solution:1
Try this code I used in my project and it works.
PHP:
$paypal_url='https://www.paypal.com/cgi-bin/webscr';
$paypal_id='example@example.com';
HTML:
<form action='<?php echo $paypal_url; ?>' method='post' name='frmPayPal1'>
<input type='hidden' name='business' value='<?php echo $paypal_id;?>'>
<input type='hidden' name='cmd' value='_xclick'>
<input type='hidden' name='item_name' value='Products Total'>
<input type='hidden' name='amount' value='<?php echo $tot;?>'>
<input type='hidden' name='no_shipping' value='1'>
<input type='hidden' name='currency_code' value='USD'>
<input type='hidden' name='handling' value='0'>
<input type='hidden' name='cancel_return' value='http://localhost/paypal/cancel.php'>
<input type='hidden' name='return' value='http://localhost/paypal/success.php'>
<input type="image" src="https://www.sandbox.paypal.com/en_US/i/btn/btn_buynowCC_LG.gif" border="0" name="submit" alt="PayPal - The safer, easier way to pay online!">
<img alt="" border="0" src="https://www.sandbox.paypal.com/en_US/i/scr/pixel.gif" width="1" height="1">
</form>