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	$112.59	13.321%	$127.5881	$127.59	$127.60	$127.60
Purchase #2	$185.94	12.413%	$209.0207	$209.02	$209.00	$209.00
Purchase #3	$161.55	6.234%	$171.621	$171.62	$171.60	$171.60
Purchase #4	$118.51	10.120%	$130.5032	$130.50	$130.50	$130.50
Purchase #5	$61.80	4.477%	$64.5668	$64.57	$64.55	$64.60
Purchase #6	$161.77	8.256%	$175.1257	$175.13	$175.15	$175.10
Purchase #7	$123.76	5.103%	$130.0755	$130.08	$130.10	$130.10
7 purchase totals =	$925.92		$1,008.5010	$1,008.51	$1,008.50	$1,008.50