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	$83.76	10.379%	$92.4535	$92.45	$92.45	$92.50
Purchase #2	$244.54	3.218%	$252.4093	$252.41	$252.40	$252.40
Purchase #3	$247.70	3.419%	$256.1689	$256.17	$256.15	$256.20
Purchase #4	$42.27	8.143%	$45.712	$45.71	$45.70	$45.70
Purchase #5	$226.55	13.669%	$257.5171	$257.52	$257.50	$257.50
Purchase #6	$35.64	7.435%	$38.2898	$38.29	$38.30	$38.30
Purchase #7	$83.67	7.288%	$89.7679	$89.77	$89.75	$89.80
7 purchase totals =	$964.13		$1,032.3185	$1,032.32	$1,032.25	$1,032.40