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	$57.57	9.212%	$62.8733	$62.87	$62.85	$62.90
Purchase #2	$71.67	6.122%	$76.0576	$76.06	$76.05	$76.10
Purchase #3	$34.64	12.538%	$38.9832	$38.98	$39.00	$39.00
Purchase #4	$169.52	13.458%	$192.334	$192.33	$192.35	$192.30
Purchase #5	$80.87	11.401%	$90.09	$90.09	$90.10	$90.10
Purchase #6	$18.61	3.620%	$19.2837	$19.28	$19.30	$19.30
Purchase #7	$243.40	4.187%	$253.5912	$253.59	$253.60	$253.60
7 purchase totals =	$676.28		$733.2130	$733.20	$733.25	$733.30