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	$158.60	9.333%	$173.4021	$173.40	$173.40	$173.40
Purchase #2	$123.60	5.547%	$130.4561	$130.46	$130.45	$130.50
Purchase #3	$28.46	13.148%	$32.2019	$32.20	$32.20	$32.20
Purchase #4	$245.63	8.676%	$266.9409	$266.94	$266.95	$266.90
Purchase #5	$237.82	4.116%	$247.6087	$247.61	$247.60	$247.60
Purchase #6	$46.79	11.317%	$52.0852	$52.09	$52.10	$52.10
Purchase #7	$140.91	12.831%	$158.9902	$158.99	$159.00	$159.00
7 purchase totals =	$981.81		$1,061.6851	$1,061.69	$1,061.70	$1,061.70