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	$219.25	8.273%	$237.3886	$237.39	$237.40	$237.40
Purchase #2	$65.48	11.184%	$72.8033	$72.80	$72.80	$72.80
Purchase #3	$87.27	13.473%	$99.0279	$99.03	$99.05	$99.00
Purchase #4	$197.55	6.227%	$209.8514	$209.85	$209.85	$209.90
Purchase #5	$21.37	10.693%	$23.6551	$23.66	$23.65	$23.70
Purchase #6	$67.99	4.527%	$71.0679	$71.07	$71.05	$71.10
Purchase #7	$43.32	5.181%	$45.5644	$45.56	$45.55	$45.60
7 purchase totals =	$702.23		$759.3586	$759.36	$759.35	$759.50