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	$83.31	4.367%	$86.9481	$86.95	$86.95	$86.90
Purchase #2	$29.48	12.683%	$33.2189	$33.22	$33.20	$33.20
Purchase #3	$176.66	7.855%	$190.5366	$190.54	$190.55	$190.50
Purchase #4	$209.49	9.149%	$228.6562	$228.66	$228.65	$228.70
Purchase #5	$241.38	3.328%	$249.4131	$249.41	$249.40	$249.40
Purchase #6	$7.38	7.661%	$7.9454	$7.95	$7.95	$7.90
Purchase #7	$144.84	3.793%	$150.3338	$150.33	$150.35	$150.30
7 purchase totals =	$892.54		$947.0521	$947.06	$947.05	$946.90