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	$241.62	8.685%	$262.6047	$262.60	$262.60	$262.60
Purchase #2	$54.56	5.624%	$57.6285	$57.63	$57.65	$57.60
Purchase #3	$31.62	5.743%	$33.4359	$33.44	$33.45	$33.40
Purchase #4	$104.26	13.744%	$118.5895	$118.59	$118.60	$118.60
Purchase #5	$32.69	9.769%	$35.8835	$35.88	$35.90	$35.90
Purchase #6	$58.46	5.490%	$61.6695	$61.67	$61.65	$61.70
Purchase #7	$89.27	3.574%	$92.4605	$92.46	$92.45	$92.50
7 purchase totals =	$612.48		$662.2721	$662.27	$662.30	$662.30