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	$224.70	7.222%	$240.9278	$240.93	$240.95	$240.90
Purchase #2	$116.73	9.218%	$127.4902	$127.49	$127.50	$127.50
Purchase #3	$139.25	6.209%	$147.896	$147.90	$147.90	$147.90
Purchase #4	$139.55	11.711%	$155.8927	$155.89	$155.90	$155.90
Purchase #5	$145.57	6.154%	$154.5284	$154.53	$154.55	$154.50
Purchase #6	$167.93	10.863%	$186.1722	$186.17	$186.15	$186.20
Purchase #7	$41.28	3.347%	$42.6616	$42.66	$42.65	$42.70
7 purchase totals =	$975.01		$1,055.5689	$1,055.57	$1,055.60	$1,055.60