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	$130.44	8.439%	$141.4478	$141.45	$141.45	$141.40
Purchase #2	$190.86	5.586%	$201.5214	$201.52	$201.50	$201.50
Purchase #3	$113.84	3.228%	$117.5148	$117.51	$117.50	$117.50
Purchase #4	$238.34	6.175%	$253.0575	$253.06	$253.05	$253.10
Purchase #5	$188.59	3.610%	$195.3981	$195.40	$195.40	$195.40
Purchase #6	$136.59	10.500%	$150.932	$150.93	$150.95	$150.90
Purchase #7	$50.29	3.259%	$51.929	$51.93	$51.95	$51.90
7 purchase totals =	$1,048.95		$1,111.8006	$1,111.80	$1,111.80	$1,111.70