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	$163.95	10.683%	$181.4648	$181.46	$181.45	$181.50
Purchase #2	$88.32	9.144%	$96.396	$96.40	$96.40	$96.40
Purchase #3	$240.51	10.526%	$265.8261	$265.83	$265.85	$265.80
Purchase #4	$51.91	8.637%	$56.3935	$56.39	$56.40	$56.40
Purchase #5	$53.57	11.294%	$59.6202	$59.62	$59.60	$59.60
Purchase #6	$152.46	12.521%	$171.5495	$171.55	$171.55	$171.50
Purchase #7	$160.84	13.102%	$181.9133	$181.91	$181.90	$181.90
7 purchase totals =	$911.56		$1,013.1634	$1,013.16	$1,013.15	$1,013.10