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	$146.48	5.234%	$154.1468	$154.15	$154.15	$154.10
Purchase #2	$158.47	9.266%	$173.1538	$173.15	$173.15	$173.20
Purchase #3	$203.47	9.132%	$222.0509	$222.05	$222.05	$222.10
Purchase #4	$22.42	11.117%	$24.9124	$24.91	$24.90	$24.90
Purchase #5	$187.34	6.648%	$199.7944	$199.79	$199.80	$199.80
Purchase #6	$89.72	11.872%	$100.3716	$100.37	$100.35	$100.40
Purchase #7	$128.46	6.392%	$136.6712	$136.67	$136.65	$136.70
7 purchase totals =	$936.36		$1,011.1011	$1,011.09	$1,011.05	$1,011.20