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	$196.26	11.689%	$219.2008	$219.20	$219.20	$219.20
Purchase #2	$208.86	3.845%	$216.8907	$216.89	$216.90	$216.90
Purchase #3	$52.83	13.354%	$59.8849	$59.88	$59.90	$59.90
Purchase #4	$57.48	6.610%	$61.2794	$61.28	$61.30	$61.30
Purchase #5	$104.28	9.580%	$114.27	$114.27	$114.25	$114.30
Purchase #6	$125.79	12.587%	$141.6232	$141.62	$141.60	$141.60
Purchase #7	$207.53	6.353%	$220.7144	$220.71	$220.70	$220.70
7 purchase totals =	$953.03		$1,033.8634	$1,033.85	$1,033.85	$1,033.90