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	$196.40	10.662%	$217.3402	$217.34	$217.35	$217.30
Purchase #2	$63.42	13.439%	$71.943	$71.94	$71.95	$71.90
Purchase #3	$153.35	13.798%	$174.5092	$174.51	$174.50	$174.50
Purchase #4	$34.61	10.472%	$38.2344	$38.23	$38.25	$38.20
Purchase #5	$116.51	13.254%	$131.9522	$131.95	$131.95	$132.00
Purchase #6	$133.87	11.373%	$149.095	$149.10	$149.10	$149.10
Purchase #7	$173.64	7.779%	$187.1475	$187.15	$187.15	$187.10
7 purchase totals =	$871.80		$970.2215	$970.22	$970.25	$970.10