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	$111.46	4.169%	$116.1068	$116.11	$116.10	$116.10
Purchase #2	$17.58	4.529%	$18.3762	$18.38	$18.40	$18.40
Purchase #3	$145.57	13.682%	$165.4869	$165.49	$165.50	$165.50
Purchase #4	$175.86	3.673%	$182.3193	$182.32	$182.30	$182.30
Purchase #5	$140.38	3.762%	$145.6611	$145.66	$145.65	$145.70
Purchase #6	$5.28	13.685%	$6.0026	$6.00	$6.00	$6.00
Purchase #7	$58.33	5.339%	$61.4442	$61.44	$61.45	$61.40
7 purchase totals =	$654.46		$695.3971	$695.40	$695.40	$695.40