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	$78.96	5.837%	$83.5689	$83.57	$83.55	$83.60
Purchase #2	$12.27	6.569%	$13.076	$13.08	$13.10	$13.10
Purchase #3	$213.32	4.536%	$222.9962	$223.00	$223.00	$223.00
Purchase #4	$233.72	13.648%	$265.6181	$265.62	$265.60	$265.60
Purchase #5	$186.30	11.212%	$207.188	$207.19	$207.20	$207.20
Purchase #6	$200.89	13.185%	$227.3773	$227.38	$227.40	$227.40
Purchase #7	$108.98	13.615%	$123.8176	$123.82	$123.80	$123.80
7 purchase totals =	$1,034.44		$1,143.6421	$1,143.66	$1,143.65	$1,143.70