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	$148.37	10.769%	$164.348	$164.35	$164.35	$164.30
Purchase #2	$16.91	11.719%	$18.8917	$18.89	$18.90	$18.90
Purchase #3	$17.76	7.151%	$19.03	$19.03	$19.05	$19.00
Purchase #4	$202.78	4.312%	$211.5239	$211.52	$211.50	$211.50
Purchase #5	$127.59	10.234%	$140.6476	$140.65	$140.65	$140.60
Purchase #6	$226.89	8.667%	$246.5546	$246.55	$246.55	$246.60
Purchase #7	$249.27	3.308%	$257.5159	$257.52	$257.50	$257.50
7 purchase totals =	$989.57		$1,058.5117	$1,058.51	$1,058.50	$1,058.40