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	$206.46	4.634%	$216.0274	$216.03	$216.05	$216.00
Purchase #2	$132.70	7.302%	$142.3898	$142.39	$142.40	$142.40
Purchase #3	$198.52	11.453%	$221.2565	$221.26	$221.25	$221.30
Purchase #4	$115.80	13.452%	$131.3774	$131.38	$131.40	$131.40
Purchase #5	$98.64	13.716%	$112.1695	$112.17	$112.15	$112.20
Purchase #6	$164.75	5.173%	$173.2725	$173.27	$173.25	$173.30
Purchase #7	$26.73	8.105%	$28.8965	$28.90	$28.90	$28.90
7 purchase totals =	$943.60		$1,025.3896	$1,025.40	$1,025.40	$1,025.50