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	$56.71	8.685%	$61.6353	$61.64	$61.65	$61.60
Purchase #2	$212.93	6.716%	$227.2304	$227.23	$227.25	$227.20
Purchase #3	$86.77	8.679%	$94.3008	$94.30	$94.30	$94.30
Purchase #4	$5.34	8.149%	$5.7752	$5.78	$5.80	$5.80
Purchase #5	$66.42	10.730%	$73.5469	$73.55	$73.55	$73.50
Purchase #6	$48.90	13.266%	$55.3871	$55.39	$55.40	$55.40
Purchase #7	$180.87	8.490%	$196.2259	$196.23	$196.25	$196.20
7 purchase totals =	$657.94		$714.1016	$714.12	$714.20	$714.00