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	$49.28	5.520%	$52.0003	$52.00	$52.00	$52.00
Purchase #2	$26.36	13.380%	$29.887	$29.89	$29.90	$29.90
Purchase #3	$72.83	13.204%	$82.4465	$82.45	$82.45	$82.40
Purchase #4	$217.25	4.779%	$227.6324	$227.63	$227.65	$227.60
Purchase #5	$160.46	7.804%	$172.9823	$172.98	$173.00	$173.00
Purchase #6	$94.43	11.146%	$104.9552	$104.96	$104.95	$105.00
Purchase #7	$203.67	10.721%	$225.5055	$225.51	$225.50	$225.50
7 purchase totals =	$824.28		$895.4092	$895.42	$895.45	$895.40