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	$104.42	6.377%	$111.0789	$111.08	$111.10	$111.10
Purchase #2	$62.95	7.370%	$67.5894	$67.59	$67.60	$67.60
Purchase #3	$11.37	5.147%	$11.9552	$11.96	$11.95	$12.00
Purchase #4	$229.96	11.369%	$256.1042	$256.10	$256.10	$256.10
Purchase #5	$225.91	3.359%	$233.4983	$233.50	$233.50	$233.50
Purchase #6	$53.79	5.697%	$56.8544	$56.85	$56.85	$56.90
Purchase #7	$7.62	11.754%	$8.5157	$8.52	$8.50	$8.50
7 purchase totals =	$696.02		$745.5961	$745.60	$745.60	$745.70