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	$200.40	4.491%	$209.4	$209.40	$209.40	$209.40
Purchase #2	$24.51	13.440%	$27.8041	$27.80	$27.80	$27.80
Purchase #3	$39.25	4.111%	$40.8636	$40.86	$40.85	$40.90
Purchase #4	$190.51	12.229%	$213.8075	$213.81	$213.80	$213.80
Purchase #5	$153.38	12.137%	$171.9957	$172.00	$172.00	$172.00
Purchase #6	$214.62	3.639%	$222.43	$222.43	$222.45	$222.40
Purchase #7	$143.63	11.845%	$160.643	$160.64	$160.65	$160.60
7 purchase totals =	$966.30		$1,046.9439	$1,046.94	$1,046.95	$1,046.90