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	$218.44	10.509%	$241.3959	$241.40	$241.40	$241.40
Purchase #2	$15.64	5.604%	$16.5165	$16.52	$16.50	$16.50
Purchase #3	$196.51	7.185%	$210.6292	$210.63	$210.65	$210.60
Purchase #4	$40.75	9.162%	$44.4835	$44.48	$44.50	$44.50
Purchase #5	$85.78	5.239%	$90.274	$90.27	$90.25	$90.30
Purchase #6	$215.69	12.859%	$243.4256	$243.43	$243.45	$243.40
Purchase #7	$154.65	10.209%	$170.4382	$170.44	$170.45	$170.40
7 purchase totals =	$927.46		$1,017.1629	$1,017.17	$1,017.20	$1,017.10