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	$95.64	6.252%	$101.6194	$101.62	$101.60	$101.60
Purchase #2	$50.85	11.293%	$56.5925	$56.59	$56.60	$56.60
Purchase #3	$127.60	11.360%	$142.0954	$142.10	$142.10	$142.10
Purchase #4	$95.37	12.274%	$107.0757	$107.08	$107.10	$107.10
Purchase #5	$88.74	11.754%	$99.1705	$99.17	$99.15	$99.20
Purchase #6	$31.37	4.403%	$32.7512	$32.75	$32.75	$32.80
Purchase #7	$217.69	13.422%	$246.9084	$246.91	$246.90	$246.90
7 purchase totals =	$707.26		$786.2131	$786.22	$786.20	$786.30