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	$194.59	8.533%	$211.1944	$211.19	$211.20	$211.20
Purchase #2	$205.92	4.437%	$215.0567	$215.06	$215.05	$215.10
Purchase #3	$216.98	9.453%	$237.4911	$237.49	$237.50	$237.50
Purchase #4	$48.60	12.109%	$54.485	$54.49	$54.50	$54.50
Purchase #5	$173.85	7.462%	$186.8227	$186.82	$186.80	$186.80
Purchase #6	$10.60	11.377%	$11.806	$11.81	$11.80	$11.80
Purchase #7	$129.83	12.854%	$146.5183	$146.52	$146.50	$146.50
7 purchase totals =	$980.37		$1,063.3742	$1,063.38	$1,063.35	$1,063.40