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	$215.40	5.491%	$227.2276	$227.23	$227.25	$227.20
Purchase #2	$104.72	6.182%	$111.1938	$111.19	$111.20	$111.20
Purchase #3	$187.90	3.640%	$194.7396	$194.74	$194.75	$194.70
Purchase #4	$168.87	9.553%	$185.0022	$185.00	$185.00	$185.00
Purchase #5	$222.83	12.348%	$250.345	$250.35	$250.35	$250.30
Purchase #6	$211.45	6.764%	$225.7525	$225.75	$225.75	$225.80
Purchase #7	$130.57	13.544%	$148.2544	$148.25	$148.25	$148.30
7 purchase totals =	$1,241.74		$1,342.5151	$1,342.51	$1,342.55	$1,342.50