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	$58.98	5.509%	$62.2292	$62.23	$62.25	$62.20
Purchase #2	$108.38	3.767%	$112.4627	$112.46	$112.45	$112.50
Purchase #3	$234.72	13.568%	$266.5668	$266.57	$266.55	$266.60
Purchase #4	$224.27	13.260%	$254.0082	$254.01	$254.00	$254.00
Purchase #5	$164.33	4.725%	$172.0946	$172.09	$172.10	$172.10
Purchase #6	$141.79	8.277%	$153.526	$153.53	$153.55	$153.50
Purchase #7	$49.49	7.685%	$53.2933	$53.29	$53.30	$53.30
7 purchase totals =	$981.96		$1,074.1808	$1,074.18	$1,074.20	$1,074.20