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	$198.46	3.620%	$205.6443	$205.64	$205.65	$205.60
Purchase #2	$165.83	8.287%	$179.5723	$179.57	$179.55	$179.60
Purchase #3	$191.50	4.723%	$200.5445	$200.54	$200.55	$200.50
Purchase #4	$19.34	13.273%	$21.907	$21.91	$21.90	$21.90
Purchase #5	$185.79	3.606%	$192.4896	$192.49	$192.50	$192.50
Purchase #6	$126.94	11.713%	$141.8085	$141.81	$141.80	$141.80
Purchase #7	$98.91	12.864%	$111.6338	$111.63	$111.65	$111.60
7 purchase totals =	$986.77		$1,053.6000	$1,053.59	$1,053.60	$1,053.50