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	$168.42	11.348%	$187.5323	$187.53	$187.55	$187.50
Purchase #2	$20.82	5.146%	$21.8914	$21.89	$21.90	$21.90
Purchase #3	$43.57	11.235%	$48.4651	$48.47	$48.45	$48.50
Purchase #4	$98.43	5.871%	$104.2088	$104.21	$104.20	$104.20
Purchase #5	$11.36	10.676%	$12.5728	$12.57	$12.55	$12.60
Purchase #6	$98.67	5.756%	$104.3494	$104.35	$104.35	$104.30
Purchase #7	$222.74	11.398%	$248.1279	$248.13	$248.15	$248.10
7 purchase totals =	$664.01		$727.1477	$727.15	$727.15	$727.10