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	$213.27	10.726%	$236.1453	$236.15	$236.15	$236.10
Purchase #2	$197.94	5.409%	$208.6466	$208.65	$208.65	$208.60
Purchase #3	$6.52	8.620%	$7.082	$7.08	$7.10	$7.10
Purchase #4	$94.46	11.265%	$105.1009	$105.10	$105.10	$105.10
Purchase #5	$221.67	9.239%	$242.1501	$242.15	$242.15	$242.20
Purchase #6	$209.33	13.487%	$237.5623	$237.56	$237.55	$237.60
Purchase #7	$56.83	4.871%	$59.5982	$59.60	$59.60	$59.60
7 purchase totals =	$1,000.02		$1,096.2854	$1,096.29	$1,096.30	$1,096.30