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	$196.98	9.518%	$215.7286	$215.73	$215.75	$215.70
Purchase #2	$49.81	9.299%	$54.4418	$54.44	$54.45	$54.40
Purchase #3	$43.50	11.257%	$48.3968	$48.40	$48.40	$48.40
Purchase #4	$105.83	8.113%	$114.416	$114.42	$114.40	$114.40
Purchase #5	$191.95	9.599%	$210.3753	$210.38	$210.40	$210.40
Purchase #6	$79.83	4.750%	$83.6219	$83.62	$83.60	$83.60
Purchase #7	$190.34	13.790%	$216.5879	$216.59	$216.60	$216.60
7 purchase totals =	$858.24		$943.5683	$943.58	$943.60	$943.50