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	$41.58	11.248%	$46.2569	$46.26	$46.25	$46.30
Purchase #2	$214.69	13.472%	$243.613	$243.61	$243.60	$243.60
Purchase #3	$95.29	11.180%	$105.9434	$105.94	$105.95	$105.90
Purchase #4	$140.97	11.448%	$157.1082	$157.11	$157.10	$157.10
Purchase #5	$249.71	5.732%	$264.0234	$264.02	$264.00	$264.00
Purchase #6	$46.49	12.872%	$52.4742	$52.47	$52.45	$52.50
Purchase #7	$40.33	11.227%	$44.8578	$44.86	$44.85	$44.90
7 purchase totals =	$829.06		$914.2769	$914.27	$914.20	$914.30