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	$182.56	6.858%	$195.08	$195.08	$195.10	$195.10
Purchase #2	$178.33	9.108%	$194.5723	$194.57	$194.55	$194.60
Purchase #3	$128.29	10.259%	$141.4513	$141.45	$141.45	$141.50
Purchase #4	$196.29	9.194%	$214.3369	$214.34	$214.35	$214.30
Purchase #5	$169.71	5.434%	$178.932	$178.93	$178.95	$178.90
Purchase #6	$155.46	11.236%	$172.9275	$172.93	$172.95	$172.90
Purchase #7	$233.86	9.574%	$256.2498	$256.25	$256.25	$256.20
7 purchase totals =	$1,244.50		$1,353.5498	$1,353.55	$1,353.60	$1,353.50