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	$41.83	13.768%	$47.5892	$47.59	$47.60	$47.60
Purchase #2	$153.46	11.186%	$170.626	$170.63	$170.65	$170.60
Purchase #3	$34.51	9.191%	$37.6818	$37.68	$37.70	$37.70
Purchase #4	$129.56	9.356%	$141.6816	$141.68	$141.70	$141.70
Purchase #5	$96.70	3.273%	$99.865	$99.87	$99.85	$99.90
Purchase #6	$105.50	3.819%	$109.529	$109.53	$109.55	$109.50
Purchase #7	$103.58	12.653%	$116.686	$116.69	$116.70	$116.70
7 purchase totals =	$665.14		$723.6586	$723.67	$723.75	$723.70