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	$105.80	4.621%	$110.689	$110.69	$110.70	$110.70
Purchase #2	$204.31	6.484%	$217.5575	$217.56	$217.55	$217.60
Purchase #3	$103.72	5.808%	$109.7441	$109.74	$109.75	$109.70
Purchase #4	$138.26	10.531%	$152.8202	$152.82	$152.80	$152.80
Purchase #5	$58.61	10.662%	$64.859	$64.86	$64.85	$64.90
Purchase #6	$107.42	8.465%	$116.5131	$116.51	$116.50	$116.50
Purchase #7	$99.81	3.284%	$103.0878	$103.09	$103.10	$103.10
7 purchase totals =	$817.93		$875.2707	$875.27	$875.25	$875.30