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	$183.79	7.107%	$196.852	$196.85	$196.85	$196.90
Purchase #2	$62.69	5.366%	$66.0539	$66.05	$66.05	$66.10
Purchase #3	$213.36	5.265%	$224.5934	$224.59	$224.60	$224.60
Purchase #4	$43.27	3.531%	$44.7979	$44.80	$44.80	$44.80
Purchase #5	$41.34	10.553%	$45.7026	$45.70	$45.70	$45.70
Purchase #6	$10.77	7.584%	$11.5868	$11.59	$11.60	$11.60
Purchase #7	$143.42	13.638%	$162.9796	$162.98	$163.00	$163.00
7 purchase totals =	$698.64		$752.5662	$752.56	$752.60	$752.70