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	$114.40	8.335%	$123.9352	$123.94	$123.95	$123.90
Purchase #2	$56.79	5.323%	$59.8129	$59.81	$59.80	$59.80
Purchase #3	$69.80	5.333%	$73.5224	$73.52	$73.50	$73.50
Purchase #4	$168.97	8.644%	$183.5758	$183.58	$183.60	$183.60
Purchase #5	$149.62	12.487%	$168.303	$168.30	$168.30	$168.30
Purchase #6	$50.57	6.166%	$53.6881	$53.69	$53.70	$53.70
Purchase #7	$115.25	7.639%	$124.0539	$124.05	$124.05	$124.10
7 purchase totals =	$725.40		$786.8913	$786.89	$786.90	$786.90