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	$50.98	3.436%	$52.7317	$52.73	$52.75	$52.70
Purchase #2	$55.59	7.484%	$59.7504	$59.75	$59.75	$59.80
Purchase #3	$229.81	5.258%	$241.8934	$241.89	$241.90	$241.90
Purchase #4	$197.78	10.209%	$217.9714	$217.97	$217.95	$218.00
Purchase #5	$43.26	7.688%	$46.5858	$46.59	$46.60	$46.60
Purchase #6	$132.72	8.596%	$144.1286	$144.13	$144.15	$144.10
Purchase #7	$184.42	8.651%	$200.3742	$200.37	$200.35	$200.40
7 purchase totals =	$894.56		$963.4355	$963.43	$963.45	$963.50