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	$164.41	6.524%	$175.1361	$175.14	$175.15	$175.10
Purchase #2	$33.26	4.157%	$34.6426	$34.64	$34.65	$34.60
Purchase #3	$166.78	3.446%	$172.5272	$172.53	$172.55	$172.50
Purchase #4	$40.71	10.725%	$45.0761	$45.08	$45.10	$45.10
Purchase #5	$102.95	8.352%	$111.5484	$111.55	$111.55	$111.50
Purchase #6	$197.73	8.757%	$215.0452	$215.05	$215.05	$215.00
Purchase #7	$93.85	13.361%	$106.3893	$106.39	$106.40	$106.40
7 purchase totals =	$799.69		$860.3649	$860.38	$860.45	$860.20