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	$146.50	4.481%	$153.0647	$153.06	$153.05	$153.10
Purchase #2	$177.60	3.506%	$183.8267	$183.83	$183.85	$183.80
Purchase #3	$229.56	10.549%	$253.7763	$253.78	$253.80	$253.80
Purchase #4	$50.92	4.443%	$53.1824	$53.18	$53.20	$53.20
Purchase #5	$172.96	12.798%	$195.0954	$195.10	$195.10	$195.10
Purchase #6	$89.59	12.700%	$100.9679	$100.97	$100.95	$101.00
Purchase #7	$136.58	4.358%	$142.5322	$142.53	$142.55	$142.50
7 purchase totals =	$1,003.71		$1,082.4456	$1,082.45	$1,082.50	$1,082.50