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	$60.97	3.299%	$62.9814	$62.98	$63.00	$63.00
Purchase #2	$245.57	7.464%	$263.8993	$263.90	$263.90	$263.90
Purchase #3	$105.26	5.748%	$111.3103	$111.31	$111.30	$111.30
Purchase #4	$242.84	5.771%	$256.8543	$256.85	$256.85	$256.90
Purchase #5	$74.89	3.412%	$77.4452	$77.45	$77.45	$77.40
Purchase #6	$51.45	4.856%	$53.9484	$53.95	$53.95	$53.90
Purchase #7	$187.46	10.555%	$207.2464	$207.25	$207.25	$207.20
7 purchase totals =	$968.44		$1,033.6853	$1,033.69	$1,033.70	$1,033.60