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	$214.27	11.109%	$238.0733	$238.07	$238.05	$238.10
Purchase #2	$245.99	10.372%	$271.5041	$271.50	$271.50	$271.50
Purchase #3	$113.39	12.503%	$127.5672	$127.57	$127.55	$127.60
Purchase #4	$165.93	12.669%	$186.9517	$186.95	$186.95	$187.00
Purchase #5	$184.97	6.228%	$196.4899	$196.49	$196.50	$196.50
Purchase #6	$176.94	6.549%	$188.5278	$188.53	$188.55	$188.50
Purchase #7	$122.80	10.823%	$136.0906	$136.09	$136.10	$136.10
7 purchase totals =	$1,224.29		$1,345.2046	$1,345.20	$1,345.20	$1,345.30