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	$224.86	8.538%	$244.0585	$244.06	$244.05	$244.10
Purchase #2	$164.97	4.357%	$172.1577	$172.16	$172.15	$172.20
Purchase #3	$143.79	13.604%	$163.3512	$163.35	$163.35	$163.40
Purchase #4	$130.93	10.273%	$144.3804	$144.38	$144.40	$144.40
Purchase #5	$180.84	8.522%	$196.2512	$196.25	$196.25	$196.30
Purchase #6	$149.49	3.763%	$155.1153	$155.12	$155.10	$155.10
Purchase #7	$100.71	3.415%	$104.1492	$104.15	$104.15	$104.10
7 purchase totals =	$1,095.59		$1,179.4635	$1,179.47	$1,179.45	$1,179.60