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	$194.59	6.592%	$207.4174	$207.42	$207.40	$207.40
Purchase #2	$33.59	6.665%	$35.8288	$35.83	$35.85	$35.80
Purchase #3	$139.83	4.301%	$145.8441	$145.84	$145.85	$145.80
Purchase #4	$78.62	11.454%	$87.6251	$87.63	$87.65	$87.60
Purchase #5	$72.66	8.574%	$78.8899	$78.89	$78.90	$78.90
Purchase #6	$246.94	6.534%	$263.0751	$263.08	$263.10	$263.10
Purchase #7	$213.58	13.763%	$242.975	$242.98	$243.00	$243.00
7 purchase totals =	$979.81		$1,061.6554	$1,061.67	$1,061.75	$1,061.60