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	$218.61	11.626%	$244.0256	$244.03	$244.05	$244.00
Purchase #2	$96.54	4.439%	$100.8254	$100.83	$100.85	$100.80
Purchase #3	$20.70	12.680%	$23.3248	$23.32	$23.30	$23.30
Purchase #4	$150.77	5.297%	$158.7563	$158.76	$158.75	$158.80
Purchase #5	$243.66	5.351%	$256.6982	$256.70	$256.70	$256.70
Purchase #6	$32.54	5.671%	$34.3853	$34.39	$34.40	$34.40
Purchase #7	$242.51	13.657%	$275.6296	$275.63	$275.65	$275.60
7 purchase totals =	$1,005.33		$1,093.6452	$1,093.66	$1,093.70	$1,093.60