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	$233.62	7.851%	$251.9615	$251.96	$251.95	$252.00
Purchase #2	$238.56	3.540%	$247.005	$247.01	$247.00	$247.00
Purchase #3	$211.29	13.477%	$239.7656	$239.77	$239.75	$239.80
Purchase #4	$167.82	6.557%	$178.824	$178.82	$178.80	$178.80
Purchase #5	$177.52	12.586%	$199.8627	$199.86	$199.85	$199.90
Purchase #6	$141.64	7.814%	$152.7077	$152.71	$152.70	$152.70
Purchase #7	$176.38	11.342%	$196.385	$196.39	$196.40	$196.40
7 purchase totals =	$1,346.83		$1,466.5115	$1,466.52	$1,466.45	$1,466.60