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	$119.95	9.847%	$131.7615	$131.76	$131.75	$131.80
Purchase #2	$114.44	11.509%	$127.6109	$127.61	$127.60	$127.60
Purchase #3	$40.81	13.577%	$46.3508	$46.35	$46.35	$46.40
Purchase #4	$247.43	6.456%	$263.4041	$263.40	$263.40	$263.40
Purchase #5	$68.38	13.510%	$77.6181	$77.62	$77.60	$77.60
Purchase #6	$161.46	3.546%	$167.1854	$167.19	$167.20	$167.20
Purchase #7	$75.31	8.272%	$81.5396	$81.54	$81.55	$81.50
7 purchase totals =	$827.78		$895.4704	$895.47	$895.45	$895.50