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	$175.37	5.410%	$184.8575	$184.86	$184.85	$184.90
Purchase #2	$199.94	6.328%	$212.5922	$212.59	$212.60	$212.60
Purchase #3	$49.36	6.497%	$52.5669	$52.57	$52.55	$52.60
Purchase #4	$195.29	11.857%	$218.4455	$218.45	$218.45	$218.40
Purchase #5	$40.38	6.203%	$42.8848	$42.88	$42.90	$42.90
Purchase #6	$117.35	8.327%	$127.1217	$127.12	$127.10	$127.10
Purchase #7	$196.35	10.769%	$217.4949	$217.49	$217.50	$217.50
7 purchase totals =	$974.04		$1,055.9635	$1,055.96	$1,055.95	$1,056.00