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	$193.54	11.733%	$216.248	$216.25	$216.25	$216.20
Purchase #2	$243.87	11.366%	$271.5883	$271.59	$271.60	$271.60
Purchase #3	$151.70	4.737%	$158.886	$158.89	$158.90	$158.90
Purchase #4	$153.27	13.272%	$173.612	$173.61	$173.60	$173.60
Purchase #5	$173.82	4.705%	$181.9982	$182.00	$182.00	$182.00
Purchase #6	$182.41	6.802%	$194.8175	$194.82	$194.80	$194.80
Purchase #7	$239.79	10.647%	$265.3204	$265.32	$265.30	$265.30
7 purchase totals =	$1,338.40		$1,462.4704	$1,462.48	$1,462.45	$1,462.40