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	$144.48	12.314%	$162.2713	$162.27	$162.25	$162.30
Purchase #2	$205.37	12.579%	$231.2035	$231.20	$231.20	$231.20
Purchase #3	$72.77	7.732%	$78.3966	$78.40	$78.40	$78.40
Purchase #4	$145.77	11.243%	$162.1589	$162.16	$162.15	$162.20
Purchase #5	$13.30	5.321%	$14.0077	$14.01	$14.00	$14.00
Purchase #6	$239.94	13.366%	$272.0104	$272.01	$272.00	$272.00
Purchase #7	$141.45	5.274%	$148.9101	$148.91	$148.90	$148.90
7 purchase totals =	$963.08		$1,068.9585	$1,068.96	$1,068.90	$1,069.00