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	$152.54	6.815%	$162.9356	$162.94	$162.95	$162.90
Purchase #2	$153.47	13.322%	$173.9153	$173.92	$173.90	$173.90
Purchase #3	$180.70	5.455%	$190.5572	$190.56	$190.55	$190.60
Purchase #4	$204.60	9.504%	$224.0452	$224.05	$224.05	$224.00
Purchase #5	$90.94	3.698%	$94.303	$94.30	$94.30	$94.30
Purchase #6	$232.88	11.451%	$259.5471	$259.55	$259.55	$259.50
Purchase #7	$16.50	11.820%	$18.4503	$18.45	$18.45	$18.50
7 purchase totals =	$1,031.63		$1,123.7537	$1,123.77	$1,123.75	$1,123.70