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	$184.44	7.422%	$198.1291	$198.13	$198.15	$198.10
Purchase #2	$131.92	12.382%	$148.2543	$148.25	$148.25	$148.30
Purchase #3	$109.56	4.710%	$114.7203	$114.72	$114.70	$114.70
Purchase #4	$57.70	6.802%	$61.6248	$61.62	$61.60	$61.60
Purchase #5	$134.61	11.531%	$150.1319	$150.13	$150.15	$150.10
Purchase #6	$9.27	11.527%	$10.3386	$10.34	$10.35	$10.30
Purchase #7	$46.67	5.102%	$49.0511	$49.05	$49.05	$49.10
7 purchase totals =	$674.17		$732.2501	$732.24	$732.25	$732.20