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	$177.78	7.768%	$191.59	$191.59	$191.60	$191.60
Purchase #2	$205.50	3.177%	$212.0287	$212.03	$212.05	$212.00
Purchase #3	$43.36	12.319%	$48.7015	$48.70	$48.70	$48.70
Purchase #4	$199.40	7.400%	$214.1556	$214.16	$214.15	$214.20
Purchase #5	$26.47	3.705%	$27.4507	$27.45	$27.45	$27.50
Purchase #6	$94.82	6.111%	$100.6145	$100.61	$100.60	$100.60
Purchase #7	$141.61	6.864%	$151.3301	$151.33	$151.35	$151.30
7 purchase totals =	$888.94		$945.8711	$945.87	$945.90	$945.90