Let's do some math ..  Rounding examples of 7 random hypothetical purchases:
Case	Tag   Price	Sales   Tax %	Raw Total   Incl. Sales Tax	Rounded   to Penny	Rounded   to Nickel	Rounded   to Dime
Purchase #1	$241.93	8.687%	$262.9465	$262.95	$262.95	$262.90
Purchase #2	$10.39	10.384%	$11.4689	$11.47	$11.45	$11.50
Purchase #3	$81.50	11.449%	$90.8309	$90.83	$90.85	$90.80
Purchase #4	$30.62	10.803%	$33.9279	$33.93	$33.95	$33.90
Purchase #5	$61.27	7.271%	$65.7249	$65.72	$65.70	$65.70
Purchase #6	$103.36	13.614%	$117.4314	$117.43	$117.45	$117.40
Purchase #7	$74.91	10.416%	$82.7126	$82.71	$82.70	$82.70
7 purchase totals =	$603.98		$665.0431	$665.04	$665.05	$664.90