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	$89.36	10.199%	$98.4738	$98.47	$98.45	$98.50
Purchase #2	$50.95	13.105%	$57.627	$57.63	$57.65	$57.60
Purchase #3	$106.78	5.444%	$112.5931	$112.59	$112.60	$112.60
Purchase #4	$158.80	11.348%	$176.8206	$176.82	$176.80	$176.80
Purchase #5	$247.73	3.623%	$256.7053	$256.71	$256.70	$256.70
Purchase #6	$218.62	3.341%	$225.9241	$225.92	$225.90	$225.90
Purchase #7	$139.27	11.225%	$154.9031	$154.90	$154.90	$154.90
7 purchase totals =	$1,011.51		$1,083.0470	$1,083.04	$1,083.00	$1,083.00