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	$197.83	7.642%	$212.9482	$212.95	$212.95	$212.90
Purchase #2	$50.80	5.393%	$53.5396	$53.54	$53.55	$53.50
Purchase #3	$79.72	4.485%	$83.2954	$83.30	$83.30	$83.30
Purchase #4	$109.81	7.564%	$118.116	$118.12	$118.10	$118.10
Purchase #5	$165.67	11.521%	$184.7568	$184.76	$184.75	$184.80
Purchase #6	$239.80	8.120%	$259.2718	$259.27	$259.25	$259.30
Purchase #7	$153.82	11.569%	$171.6154	$171.62	$171.60	$171.60
7 purchase totals =	$997.45		$1,083.5432	$1,083.56	$1,083.50	$1,083.50