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	$158.27	11.203%	$176.001	$176.00	$176.00	$176.00
Purchase #2	$207.29	9.256%	$226.4768	$226.48	$226.50	$226.50
Purchase #3	$112.84	12.181%	$126.585	$126.59	$126.60	$126.60
Purchase #4	$19.33	5.451%	$20.3837	$20.38	$20.40	$20.40
Purchase #5	$235.27	11.741%	$262.8931	$262.89	$262.90	$262.90
Purchase #6	$112.39	13.799%	$127.8987	$127.90	$127.90	$127.90
Purchase #7	$126.30	6.392%	$134.3731	$134.37	$134.35	$134.40
7 purchase totals =	$971.69		$1,074.6114	$1,074.61	$1,074.65	$1,074.70