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	$210.55	11.357%	$234.4622	$234.46	$234.45	$234.50
Purchase #2	$225.72	13.338%	$255.8265	$255.83	$255.85	$255.80
Purchase #3	$155.26	11.833%	$173.6319	$173.63	$173.65	$173.60
Purchase #4	$53.82	11.392%	$59.9512	$59.95	$59.95	$60.00
Purchase #5	$157.46	11.102%	$174.9412	$174.94	$174.95	$174.90
Purchase #6	$111.61	6.107%	$118.426	$118.43	$118.45	$118.40
Purchase #7	$152.88	11.460%	$170.4	$170.40	$170.40	$170.40
7 purchase totals =	$1,067.30		$1,187.6390	$1,187.64	$1,187.70	$1,187.60