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	$98.58	13.512%	$111.9001	$111.90	$111.90	$111.90
Purchase #2	$58.43	5.679%	$61.7482	$61.75	$61.75	$61.70
Purchase #3	$26.54	4.475%	$27.7277	$27.73	$27.75	$27.70
Purchase #4	$60.40	5.367%	$63.6417	$63.64	$63.65	$63.60
Purchase #5	$42.93	8.758%	$46.6898	$46.69	$46.70	$46.70
Purchase #6	$120.41	5.820%	$127.4179	$127.42	$127.40	$127.40
Purchase #7	$29.53	13.645%	$33.5594	$33.56	$33.55	$33.60
7 purchase totals =	$436.82		$472.6848	$472.69	$472.70	$472.60