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	$173.64	11.499%	$193.6069	$193.61	$193.60	$193.60
Purchase #2	$142.86	4.721%	$149.6044	$149.60	$149.60	$149.60
Purchase #3	$29.48	9.854%	$32.385	$32.39	$32.40	$32.40
Purchase #4	$163.85	5.518%	$172.8912	$172.89	$172.90	$172.90
Purchase #5	$226.69	7.449%	$243.5761	$243.58	$243.60	$243.60
Purchase #6	$131.99	11.743%	$147.4896	$147.49	$147.50	$147.50
Purchase #7	$126.97	4.198%	$132.3002	$132.30	$132.30	$132.30
7 purchase totals =	$995.48		$1,071.8534	$1,071.86	$1,071.90	$1,071.90