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	$120.37	9.606%	$131.9327	$131.93	$131.95	$131.90
Purchase #2	$122.86	3.838%	$127.5754	$127.58	$127.60	$127.60
Purchase #3	$47.97	13.862%	$54.6196	$54.62	$54.60	$54.60
Purchase #4	$139.35	8.622%	$151.3648	$151.36	$151.35	$151.40
Purchase #5	$135.34	4.873%	$141.9351	$141.94	$141.95	$141.90
Purchase #6	$216.26	5.597%	$228.3641	$228.36	$228.35	$228.40
Purchase #7	$214.65	13.176%	$242.9323	$242.93	$242.95	$242.90
7 purchase totals =	$996.80		$1,078.7240	$1,078.72	$1,078.75	$1,078.70