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	$215.37	3.202%	$222.2661	$222.27	$222.25	$222.30
Purchase #2	$152.59	5.620%	$161.1656	$161.17	$161.15	$161.20
Purchase #3	$211.38	3.182%	$218.1061	$218.11	$218.10	$218.10
Purchase #4	$14.71	12.129%	$16.4942	$16.49	$16.50	$16.50
Purchase #5	$120.55	5.588%	$127.2863	$127.29	$127.30	$127.30
Purchase #6	$117.85	4.380%	$123.0118	$123.01	$123.00	$123.00
Purchase #7	$138.36	12.868%	$156.1642	$156.16	$156.15	$156.20
7 purchase totals =	$970.81		$1,024.4943	$1,024.50	$1,024.45	$1,024.60