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	$84.81	11.511%	$94.5725	$94.57	$94.55	$94.60
Purchase #2	$198.25	12.745%	$223.517	$223.52	$223.50	$223.50
Purchase #3	$168.88	13.430%	$191.5606	$191.56	$191.55	$191.60
Purchase #4	$75.98	8.868%	$82.7179	$82.72	$82.70	$82.70
Purchase #5	$35.26	6.160%	$37.432	$37.43	$37.45	$37.40
Purchase #6	$119.54	5.862%	$126.5474	$126.55	$126.55	$126.50
Purchase #7	$224.46	10.756%	$248.6029	$248.60	$248.60	$248.60
7 purchase totals =	$907.18		$1,004.9503	$1,004.95	$1,004.90	$1,004.90