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	$75.36	3.711%	$78.1566	$78.16	$78.15	$78.20
Purchase #2	$205.82	3.509%	$213.0422	$213.04	$213.05	$213.00
Purchase #3	$194.45	7.769%	$209.5568	$209.56	$209.55	$209.60
Purchase #4	$236.38	5.482%	$249.3384	$249.34	$249.35	$249.30
Purchase #5	$9.98	12.604%	$11.2379	$11.24	$11.25	$11.20
Purchase #6	$54.82	9.108%	$59.813	$59.81	$59.80	$59.80
Purchase #7	$206.35	10.429%	$227.8702	$227.87	$227.85	$227.90
7 purchase totals =	$983.16		$1,049.0151	$1,049.02	$1,049.00	$1,049.00