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	$190.70	7.806%	$205.586	$205.59	$205.60	$205.60
Purchase #2	$59.47	4.197%	$61.966	$61.97	$61.95	$62.00
Purchase #3	$119.33	3.570%	$123.5901	$123.59	$123.60	$123.60
Purchase #4	$215.32	11.114%	$239.2507	$239.25	$239.25	$239.30
Purchase #5	$111.49	5.306%	$117.4057	$117.41	$117.40	$117.40
Purchase #6	$74.68	6.392%	$79.4535	$79.45	$79.45	$79.50
Purchase #7	$191.53	6.228%	$203.4585	$203.46	$203.45	$203.50
7 purchase totals =	$962.52		$1,030.7105	$1,030.72	$1,030.70	$1,030.90