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	$201.29	3.514%	$208.3633	$208.36	$208.35	$208.40
Purchase #2	$145.58	9.178%	$158.9413	$158.94	$158.95	$158.90
Purchase #3	$195.46	4.821%	$204.8831	$204.88	$204.90	$204.90
Purchase #4	$97.36	10.653%	$107.7318	$107.73	$107.75	$107.70
Purchase #5	$105.56	5.721%	$111.5991	$111.60	$111.60	$111.60
Purchase #6	$46.32	10.164%	$51.028	$51.03	$51.05	$51.00
Purchase #7	$242.49	11.103%	$269.4137	$269.41	$269.40	$269.40
7 purchase totals =	$1,034.06		$1,111.9603	$1,111.95	$1,112.00	$1,111.90