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	$216.95	7.670%	$233.5901	$233.59	$233.60	$233.60
Purchase #2	$60.58	8.559%	$65.765	$65.77	$65.75	$65.80
Purchase #3	$144.53	8.475%	$156.7789	$156.78	$156.80	$156.80
Purchase #4	$94.72	6.274%	$100.6627	$100.66	$100.65	$100.70
Purchase #5	$155.39	13.798%	$176.8307	$176.83	$176.85	$176.80
Purchase #6	$156.99	8.872%	$170.9182	$170.92	$170.90	$170.90
Purchase #7	$150.92	3.368%	$156.003	$156.00	$156.00	$156.00
7 purchase totals =	$980.08		$1,060.5486	$1,060.55	$1,060.55	$1,060.60