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	$215.83	13.627%	$245.2412	$245.24	$245.25	$245.20
Purchase #2	$179.40	11.153%	$199.4085	$199.41	$199.40	$199.40
Purchase #3	$175.76	5.333%	$185.1333	$185.13	$185.15	$185.10
Purchase #4	$141.51	8.439%	$153.452	$153.45	$153.45	$153.50
Purchase #5	$140.51	7.598%	$151.1859	$151.19	$151.20	$151.20
Purchase #6	$82.71	4.848%	$86.7198	$86.72	$86.70	$86.70
Purchase #7	$210.76	5.287%	$221.9029	$221.90	$221.90	$221.90
7 purchase totals =	$1,146.48		$1,243.0436	$1,243.04	$1,243.05	$1,243.00