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	$159.65	8.725%	$173.5795	$173.58	$173.60	$173.60
Purchase #2	$158.58	9.348%	$173.4041	$173.40	$173.40	$173.40
Purchase #3	$149.65	8.413%	$162.2401	$162.24	$162.25	$162.20
Purchase #4	$48.66	11.684%	$54.3454	$54.35	$54.35	$54.30
Purchase #5	$79.33	4.144%	$82.6174	$82.62	$82.60	$82.60
Purchase #6	$187.93	6.663%	$200.4518	$200.45	$200.45	$200.50
Purchase #7	$165.52	11.147%	$183.9705	$183.97	$183.95	$184.00
7 purchase totals =	$949.32		$1,030.6088	$1,030.61	$1,030.60	$1,030.60