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	$177.60	11.575%	$198.1572	$198.16	$198.15	$198.20
Purchase #2	$163.94	11.327%	$182.5095	$182.51	$182.50	$182.50
Purchase #3	$31.57	3.436%	$32.6547	$32.65	$32.65	$32.70
Purchase #4	$18.47	10.551%	$20.4188	$20.42	$20.40	$20.40
Purchase #5	$186.50	11.209%	$207.4048	$207.40	$207.40	$207.40
Purchase #6	$118.48	12.709%	$133.5376	$133.54	$133.55	$133.50
Purchase #7	$231.26	4.587%	$241.8679	$241.87	$241.85	$241.90
7 purchase totals =	$927.82		$1,016.5505	$1,016.55	$1,016.50	$1,016.60