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	$179.69	10.713%	$198.9402	$198.94	$198.95	$198.90
Purchase #2	$86.44	4.239%	$90.1042	$90.10	$90.10	$90.10
Purchase #3	$61.89	5.136%	$65.0687	$65.07	$65.05	$65.10
Purchase #4	$227.59	11.163%	$252.9959	$253.00	$253.00	$253.00
Purchase #5	$168.47	13.347%	$190.9557	$190.96	$190.95	$191.00
Purchase #6	$140.66	11.266%	$156.5068	$156.51	$156.50	$156.50
Purchase #7	$93.70	10.679%	$103.7062	$103.71	$103.70	$103.70
7 purchase totals =	$958.44		$1,058.2777	$1,058.29	$1,058.25	$1,058.30