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	$237.39	10.654%	$262.6815	$262.68	$262.70	$262.70
Purchase #2	$235.54	6.596%	$251.0762	$251.08	$251.10	$251.10
Purchase #3	$25.39	10.673%	$28.0999	$28.10	$28.10	$28.10
Purchase #4	$163.47	6.134%	$173.4972	$173.50	$173.50	$173.50
Purchase #5	$160.30	11.329%	$178.4604	$178.46	$178.45	$178.50
Purchase #6	$39.47	11.315%	$43.936	$43.94	$43.95	$43.90
Purchase #7	$240.89	7.359%	$258.6171	$258.62	$258.60	$258.60
7 purchase totals =	$1,102.45		$1,196.3683	$1,196.38	$1,196.40	$1,196.40