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	$245.73	6.267%	$261.1299	$261.13	$261.15	$261.10
Purchase #2	$105.50	10.367%	$116.4372	$116.44	$116.45	$116.40
Purchase #3	$36.64	12.815%	$41.3354	$41.34	$41.35	$41.30
Purchase #4	$89.52	12.223%	$100.462	$100.46	$100.45	$100.50
Purchase #5	$247.40	4.119%	$257.5904	$257.59	$257.60	$257.60
Purchase #6	$182.78	4.295%	$190.6304	$190.63	$190.65	$190.60
Purchase #7	$51.80	10.538%	$57.2587	$57.26	$57.25	$57.30
7 purchase totals =	$959.37		$1,024.8440	$1,024.85	$1,024.90	$1,024.80