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	$40.98	5.452%	$43.2142	$43.21	$43.20	$43.20
Purchase #2	$173.35	13.208%	$196.2461	$196.25	$196.25	$196.20
Purchase #3	$52.90	6.371%	$56.2703	$56.27	$56.25	$56.30
Purchase #4	$94.65	7.195%	$101.4601	$101.46	$101.45	$101.50
Purchase #5	$222.27	3.873%	$230.8785	$230.88	$230.90	$230.90
Purchase #6	$233.39	6.842%	$249.3585	$249.36	$249.35	$249.40
Purchase #7	$240.47	11.103%	$267.1694	$267.17	$267.15	$267.20
7 purchase totals =	$1,058.01		$1,144.5971	$1,144.60	$1,144.55	$1,144.70