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	$206.53	7.739%	$222.5134	$222.51	$222.50	$222.50
Purchase #2	$75.31	13.510%	$85.4844	$85.48	$85.50	$85.50
Purchase #3	$234.33	12.178%	$262.8667	$262.87	$262.85	$262.90
Purchase #4	$66.38	7.595%	$71.4216	$71.42	$71.40	$71.40
Purchase #5	$35.99	5.342%	$37.9126	$37.91	$37.90	$37.90
Purchase #6	$217.92	3.161%	$224.8085	$224.81	$224.80	$224.80
Purchase #7	$127.43	11.112%	$141.59	$141.59	$141.60	$141.60
7 purchase totals =	$963.89		$1,046.5972	$1,046.59	$1,046.55	$1,046.60