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	$141.46	4.671%	$148.0676	$148.07	$148.05	$148.10
Purchase #2	$49.56	10.553%	$54.7901	$54.79	$54.80	$54.80
Purchase #3	$62.42	6.414%	$66.4236	$66.42	$66.40	$66.40
Purchase #4	$63.26	5.838%	$66.9531	$66.95	$66.95	$67.00
Purchase #5	$182.27	10.516%	$201.4375	$201.44	$201.45	$201.40
Purchase #6	$216.90	12.303%	$243.5852	$243.59	$243.60	$243.60
Purchase #7	$237.38	7.641%	$255.5182	$255.52	$255.50	$255.50
7 purchase totals =	$953.25		$1,036.7753	$1,036.78	$1,036.75	$1,036.80