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	$56.44	9.730%	$61.9316	$61.93	$61.95	$61.90
Purchase #2	$15.90	11.415%	$17.715	$17.72	$17.70	$17.70
Purchase #3	$185.71	10.301%	$204.84	$204.84	$204.85	$204.80
Purchase #4	$245.60	11.464%	$273.7556	$273.76	$273.75	$273.80
Purchase #5	$218.54	3.335%	$225.8283	$225.83	$225.85	$225.80
Purchase #6	$205.76	8.147%	$222.5233	$222.52	$222.50	$222.50
Purchase #7	$177.54	10.848%	$196.7995	$196.80	$196.80	$196.80
7 purchase totals =	$1,105.49		$1,203.3933	$1,203.40	$1,203.40	$1,203.30