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	$187.83	9.712%	$206.072	$206.07	$206.05	$206.10
Purchase #2	$42.60	7.317%	$45.717	$45.72	$45.70	$45.70
Purchase #3	$216.53	3.205%	$223.4698	$223.47	$223.45	$223.50
Purchase #4	$237.42	13.490%	$269.448	$269.45	$269.45	$269.40
Purchase #5	$25.42	9.147%	$27.7452	$27.75	$27.75	$27.70
Purchase #6	$85.81	3.158%	$88.5199	$88.52	$88.50	$88.50
Purchase #7	$141.63	9.440%	$154.9999	$155.00	$155.00	$155.00
7 purchase totals =	$937.24		$1,015.9718	$1,015.98	$1,015.90	$1,015.90