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	$204.45	7.251%	$219.2747	$219.27	$219.25	$219.30
Purchase #2	$151.47	11.253%	$168.5149	$168.51	$168.50	$168.50
Purchase #3	$85.43	8.233%	$92.4635	$92.46	$92.45	$92.50
Purchase #4	$63.82	11.381%	$71.0834	$71.08	$71.10	$71.10
Purchase #5	$147.79	5.593%	$156.0559	$156.06	$156.05	$156.10
Purchase #6	$221.52	12.235%	$248.623	$248.62	$248.60	$248.60
Purchase #7	$150.57	11.476%	$167.8494	$167.85	$167.85	$167.80
7 purchase totals =	$1,025.05		$1,123.8648	$1,123.85	$1,123.80	$1,123.90