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	$133.41	7.642%	$143.6052	$143.61	$143.60	$143.60
Purchase #2	$136.97	8.490%	$148.5988	$148.60	$148.60	$148.60
Purchase #3	$149.41	13.565%	$169.6775	$169.68	$169.70	$169.70
Purchase #4	$110.82	12.398%	$124.5595	$124.56	$124.55	$124.60
Purchase #5	$139.66	9.113%	$152.3872	$152.39	$152.40	$152.40
Purchase #6	$236.27	9.217%	$258.047	$258.05	$258.05	$258.00
Purchase #7	$176.35	3.541%	$182.5946	$182.59	$182.60	$182.60
7 purchase totals =	$1,082.89		$1,179.4698	$1,179.48	$1,179.50	$1,179.50