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	$69.66	3.733%	$72.2604	$72.26	$72.25	$72.30
Purchase #2	$206.96	3.449%	$214.0981	$214.10	$214.10	$214.10
Purchase #3	$167.88	11.432%	$187.072	$187.07	$187.05	$187.10
Purchase #4	$50.40	7.254%	$54.056	$54.06	$54.05	$54.10
Purchase #5	$26.34	11.706%	$29.4234	$29.42	$29.40	$29.40
Purchase #6	$59.65	3.260%	$61.5946	$61.59	$61.60	$61.60
Purchase #7	$77.45	3.472%	$80.1391	$80.14	$80.15	$80.10
7 purchase totals =	$658.34		$698.6436	$698.64	$698.60	$698.70