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	$10.38	5.387%	$10.9392	$10.94	$10.95	$10.90
Purchase #2	$47.49	13.779%	$54.0336	$54.03	$54.05	$54.00
Purchase #3	$78.98	8.770%	$85.9065	$85.91	$85.90	$85.90
Purchase #4	$143.71	5.400%	$151.4703	$151.47	$151.45	$151.50
Purchase #5	$177.35	8.767%	$192.8983	$192.90	$192.90	$192.90
Purchase #6	$190.90	4.440%	$199.376	$199.38	$199.40	$199.40
Purchase #7	$53.30	13.387%	$60.4353	$60.44	$60.45	$60.40
7 purchase totals =	$702.11		$755.0592	$755.07	$755.10	$755.00