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	$143.64	5.717%	$151.8519	$151.85	$151.85	$151.90
Purchase #2	$189.91	12.429%	$213.5139	$213.51	$213.50	$213.50
Purchase #3	$120.53	6.422%	$128.2704	$128.27	$128.25	$128.30
Purchase #4	$59.53	8.296%	$64.4686	$64.47	$64.45	$64.50
Purchase #5	$210.62	11.417%	$234.6665	$234.67	$234.65	$234.70
Purchase #6	$190.61	4.814%	$199.786	$199.79	$199.80	$199.80
Purchase #7	$53.68	3.312%	$55.4579	$55.46	$55.45	$55.50
7 purchase totals =	$968.52		$1,048.0152	$1,048.02	$1,047.95	$1,048.20