You will also want to clean up your print and email invoices wherever possible.
I find that the Coupon and Discount fields in the invoices leave the customer feeling like they missed some kind of pricing advantage when they ordered.
Change the Discount and Coupon Display in mail.order_data.tpl to
Code:
{if $order.discount ne "0.00"}{$lng.lbl_discount}: {include file="currency.tpl" value=$order.discount}{/if}
{if $order.coupon ne ""}{$lng.lbl_coupon_saving}: {include file="currency.tpl" value=$order.coupon_discount} ({$order.coupon}){/if}
I do the same with my taxes (Canada) because we have 2 and it only serves to confuse US and UK customers (to which they do not apply). 1 less Customer Service email to answer is one less headache.