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	$216.50	5.314%	$228.0048	$228.00	$228.00	$228.00
Purchase #2	$132.59	11.511%	$147.8524	$147.85	$147.85	$147.90
Purchase #3	$64.40	5.259%	$67.7868	$67.79	$67.80	$67.80
Purchase #4	$173.70	11.632%	$193.9048	$193.90	$193.90	$193.90
Purchase #5	$196.43	12.548%	$221.078	$221.08	$221.10	$221.10
Purchase #6	$127.93	12.105%	$143.4159	$143.42	$143.40	$143.40
Purchase #7	$47.89	10.490%	$52.9137	$52.91	$52.90	$52.90
7 purchase totals =	$959.44		$1,054.9564	$1,054.95	$1,054.95	$1,055.00