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	$185.49	6.157%	$196.9106	$196.91	$196.90	$196.90
Purchase #2	$53.78	4.561%	$56.2329	$56.23	$56.25	$56.20
Purchase #3	$127.67	3.535%	$132.1831	$132.18	$132.20	$132.20
Purchase #4	$14.69	4.671%	$15.3762	$15.38	$15.40	$15.40
Purchase #5	$210.53	4.607%	$220.2291	$220.23	$220.25	$220.20
Purchase #6	$87.68	3.269%	$90.5463	$90.55	$90.55	$90.50
Purchase #7	$12.93	8.413%	$14.0178	$14.02	$14.00	$14.00
7 purchase totals =	$692.77		$725.4960	$725.50	$725.55	$725.40