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	$82.69	3.836%	$85.862	$85.86	$85.85	$85.90
Purchase #2	$131.78	13.520%	$149.5967	$149.60	$149.60	$149.60
Purchase #3	$48.51	10.600%	$53.6521	$53.65	$53.65	$53.70
Purchase #4	$53.52	6.685%	$57.0978	$57.10	$57.10	$57.10
Purchase #5	$243.45	9.862%	$267.459	$267.46	$267.45	$267.50
Purchase #6	$82.75	3.243%	$85.4336	$85.43	$85.45	$85.40
Purchase #7	$94.92	11.701%	$106.0266	$106.03	$106.05	$106.00
7 purchase totals =	$737.62		$805.1278	$805.13	$805.15	$805.20