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	$209.77	4.373%	$218.9432	$218.94	$218.95	$218.90
Purchase #2	$219.91	4.195%	$229.1352	$229.14	$229.15	$229.10
Purchase #3	$139.43	4.266%	$145.3781	$145.38	$145.40	$145.40
Purchase #4	$243.87	6.146%	$258.8583	$258.86	$258.85	$258.90
Purchase #5	$51.76	6.369%	$55.0566	$55.06	$55.05	$55.10
Purchase #6	$244.25	8.667%	$265.4191	$265.42	$265.40	$265.40
Purchase #7	$95.79	4.770%	$100.3592	$100.36	$100.35	$100.40
7 purchase totals =	$1,204.78		$1,273.1497	$1,273.16	$1,273.15	$1,273.20