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	$229.35	5.775%	$242.595	$242.60	$242.60	$242.60
Purchase #2	$47.81	11.835%	$53.4683	$53.47	$53.45	$53.50
Purchase #3	$94.74	6.437%	$100.8384	$100.84	$100.85	$100.80
Purchase #4	$17.48	12.197%	$19.612	$19.61	$19.60	$19.60
Purchase #5	$112.45	4.377%	$117.3719	$117.37	$117.35	$117.40
Purchase #6	$6.69	11.737%	$7.4752	$7.48	$7.50	$7.50
Purchase #7	$172.65	6.514%	$183.8964	$183.90	$183.90	$183.90
7 purchase totals =	$681.17		$725.2572	$725.27	$725.25	$725.30