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	$213.33	5.832%	$225.7714	$225.77	$225.75	$225.80
Purchase #2	$16.81	10.571%	$18.587	$18.59	$18.60	$18.60
Purchase #3	$94.98	5.631%	$100.3283	$100.33	$100.35	$100.30
Purchase #4	$20.50	6.489%	$21.8302	$21.83	$21.85	$21.80
Purchase #5	$235.52	8.188%	$254.8044	$254.80	$254.80	$254.80
Purchase #6	$243.46	4.846%	$255.2581	$255.26	$255.25	$255.30
Purchase #7	$174.25	10.159%	$191.9521	$191.95	$191.95	$192.00
7 purchase totals =	$998.85		$1,068.5315	$1,068.53	$1,068.55	$1,068.60