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	$96.80	7.508%	$104.0677	$104.07	$104.05	$104.10
Purchase #2	$177.72	9.592%	$194.7669	$194.77	$194.75	$194.80
Purchase #3	$222.67	13.567%	$252.8796	$252.88	$252.90	$252.90
Purchase #4	$53.85	9.839%	$59.1483	$59.15	$59.15	$59.10
Purchase #5	$39.64	11.592%	$44.2351	$44.24	$44.25	$44.20
Purchase #6	$222.34	5.503%	$234.5754	$234.58	$234.60	$234.60
Purchase #7	$195.78	5.166%	$205.894	$205.89	$205.90	$205.90
7 purchase totals =	$1,008.80		$1,095.5670	$1,095.58	$1,095.60	$1,095.60