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	$146.66	4.510%	$153.2744	$153.27	$153.25	$153.30
Purchase #2	$145.72	4.235%	$151.8912	$151.89	$151.90	$151.90
Purchase #3	$149.41	4.205%	$155.6927	$155.69	$155.70	$155.70
Purchase #4	$80.51	3.599%	$83.4076	$83.41	$83.40	$83.40
Purchase #5	$8.93	12.587%	$10.054	$10.05	$10.05	$10.10
Purchase #6	$19.85	3.745%	$20.5934	$20.59	$20.60	$20.60
Purchase #7	$186.48	3.492%	$192.9919	$192.99	$193.00	$193.00
7 purchase totals =	$737.56		$767.9052	$767.89	$767.90	$768.00