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	$175.72	11.509%	$195.9436	$195.94	$195.95	$195.90
Purchase #2	$30.50	13.307%	$34.5586	$34.56	$34.55	$34.60
Purchase #3	$65.86	7.205%	$70.6052	$70.61	$70.60	$70.60
Purchase #4	$119.37	7.520%	$128.3466	$128.35	$128.35	$128.30
Purchase #5	$88.63	13.497%	$100.5924	$100.59	$100.60	$100.60
Purchase #6	$28.34	11.812%	$31.6875	$31.69	$31.70	$31.70
Purchase #7	$103.62	9.279%	$113.2349	$113.23	$113.25	$113.20
7 purchase totals =	$612.04		$674.9688	$674.97	$675.00	$674.90