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	$222.52	10.114%	$245.0257	$245.03	$245.05	$245.00
Purchase #2	$74.88	13.850%	$85.2509	$85.25	$85.25	$85.30
Purchase #3	$233.72	11.304%	$260.1397	$260.14	$260.15	$260.10
Purchase #4	$22.44	4.780%	$23.5126	$23.51	$23.50	$23.50
Purchase #5	$88.78	13.387%	$100.665	$100.67	$100.65	$100.70
Purchase #6	$199.53	9.836%	$219.1558	$219.16	$219.15	$219.20
Purchase #7	$104.87	5.847%	$111.0017	$111.00	$111.00	$111.00
7 purchase totals =	$946.74		$1,044.7514	$1,044.76	$1,044.75	$1,044.80