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	$162.61	9.485%	$178.0336	$178.03	$178.05	$178.00
Purchase #2	$50.66	8.504%	$54.9681	$54.97	$54.95	$55.00
Purchase #3	$195.98	7.207%	$210.1043	$210.10	$210.10	$210.10
Purchase #4	$125.86	10.491%	$139.064	$139.06	$139.05	$139.10
Purchase #5	$167.89	12.845%	$189.4555	$189.46	$189.45	$189.50
Purchase #6	$225.66	7.218%	$241.9481	$241.95	$241.95	$241.90
Purchase #7	$145.72	9.109%	$158.9936	$158.99	$159.00	$159.00
7 purchase totals =	$1,074.38		$1,172.5672	$1,172.56	$1,172.55	$1,172.60