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	$218.34	9.193%	$238.412	$238.41	$238.40	$238.40
Purchase #2	$49.49	4.142%	$51.5399	$51.54	$51.55	$51.50
Purchase #3	$97.63	11.826%	$109.1757	$109.18	$109.20	$109.20
Purchase #4	$140.27	12.337%	$157.5751	$157.58	$157.60	$157.60
Purchase #5	$212.30	4.433%	$221.7113	$221.71	$221.70	$221.70
Purchase #6	$196.91	6.664%	$210.0321	$210.03	$210.05	$210.00
Purchase #7	$116.98	5.598%	$123.5285	$123.53	$123.55	$123.50
7 purchase totals =	$1,031.92		$1,111.9746	$1,111.98	$1,112.05	$1,111.90