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	$174.85	5.527%	$184.514	$184.51	$184.50	$184.50
Purchase #2	$16.79	10.576%	$18.5657	$18.57	$18.55	$18.60
Purchase #3	$119.34	3.707%	$123.7639	$123.76	$123.75	$123.80
Purchase #4	$230.69	5.327%	$242.9789	$242.98	$243.00	$243.00
Purchase #5	$150.65	9.337%	$164.7162	$164.72	$164.70	$164.70
Purchase #6	$129.46	8.200%	$140.0757	$140.08	$140.10	$140.10
Purchase #7	$132.25	13.777%	$150.4701	$150.47	$150.45	$150.50
7 purchase totals =	$954.03		$1,025.0845	$1,025.09	$1,025.05	$1,025.20