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	$33.92	5.678%	$35.846	$35.85	$35.85	$35.80
Purchase #2	$90.84	10.523%	$100.3991	$100.40	$100.40	$100.40
Purchase #3	$207.83	11.420%	$231.5642	$231.56	$231.55	$231.60
Purchase #4	$202.80	6.373%	$215.7244	$215.72	$215.70	$215.70
Purchase #5	$190.77	11.136%	$212.0141	$212.01	$212.00	$212.00
Purchase #6	$119.56	8.825%	$130.1112	$130.11	$130.10	$130.10
Purchase #7	$111.96	12.776%	$126.264	$126.26	$126.25	$126.30
7 purchase totals =	$957.68		$1,051.9230	$1,051.91	$1,051.85	$1,051.90