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	$216.66	11.287%	$241.1144	$241.11	$241.10	$241.10
Purchase #2	$20.29	6.288%	$21.5658	$21.57	$21.55	$21.60
Purchase #3	$145.32	10.352%	$160.3635	$160.36	$160.35	$160.40
Purchase #4	$150.71	6.271%	$160.161	$160.16	$160.15	$160.20
Purchase #5	$140.26	4.127%	$146.0485	$146.05	$146.05	$146.00
Purchase #6	$92.52	11.782%	$103.4207	$103.42	$103.40	$103.40
Purchase #7	$198.60	7.193%	$212.8853	$212.89	$212.90	$212.90
7 purchase totals =	$964.36		$1,045.5592	$1,045.56	$1,045.50	$1,045.60