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	$57.31	9.291%	$62.6347	$62.63	$62.65	$62.60
Purchase #2	$84.84	5.333%	$89.3645	$89.36	$89.35	$89.40
Purchase #3	$119.82	6.788%	$127.9534	$127.95	$127.95	$128.00
Purchase #4	$67.49	13.367%	$76.5114	$76.51	$76.50	$76.50
Purchase #5	$10.44	6.137%	$11.0807	$11.08	$11.10	$11.10
Purchase #6	$9.30	9.281%	$10.1631	$10.16	$10.15	$10.20
Purchase #7	$10.67	10.645%	$11.8058	$11.81	$11.80	$11.80
7 purchase totals =	$359.87		$389.5136	$389.50	$389.50	$389.60