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	$214.90	8.664%	$233.5189	$233.52	$233.50	$233.50
Purchase #2	$76.53	5.677%	$80.8746	$80.87	$80.85	$80.90
Purchase #3	$215.53	4.762%	$225.7935	$225.79	$225.80	$225.80
Purchase #4	$72.66	4.571%	$75.9813	$75.98	$76.00	$76.00
Purchase #5	$201.97	6.406%	$214.9082	$214.91	$214.90	$214.90
Purchase #6	$114.36	4.261%	$119.2329	$119.23	$119.25	$119.20
Purchase #7	$85.62	4.629%	$89.5833	$89.58	$89.60	$89.60
7 purchase totals =	$981.57		$1,039.8927	$1,039.88	$1,039.90	$1,039.90