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	$151.34	8.547%	$164.275	$164.28	$164.30	$164.30
Purchase #2	$30.63	7.164%	$32.8243	$32.82	$32.80	$32.80
Purchase #3	$146.48	8.295%	$158.6305	$158.63	$158.65	$158.60
Purchase #4	$94.61	11.343%	$105.3416	$105.34	$105.35	$105.30
Purchase #5	$199.86	13.866%	$227.5726	$227.57	$227.55	$227.60
Purchase #6	$103.53	12.682%	$116.6597	$116.66	$116.65	$116.70
Purchase #7	$248.72	4.400%	$259.6637	$259.66	$259.65	$259.70
7 purchase totals =	$975.17		$1,064.9674	$1,064.96	$1,064.95	$1,065.00