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	$117.45	7.625%	$126.4056	$126.41	$126.40	$126.40
Purchase #2	$160.61	7.595%	$172.8083	$172.81	$172.80	$172.80
Purchase #3	$248.30	8.506%	$269.4204	$269.42	$269.40	$269.40
Purchase #4	$61.29	6.223%	$65.1041	$65.10	$65.10	$65.10
Purchase #5	$126.89	13.194%	$143.6319	$143.63	$143.65	$143.60
Purchase #6	$248.86	11.770%	$278.1508	$278.15	$278.15	$278.20
Purchase #7	$233.46	5.248%	$245.712	$245.71	$245.70	$245.70
7 purchase totals =	$1,196.86		$1,301.2331	$1,301.23	$1,301.20	$1,301.20