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	$111.58	13.389%	$126.5194	$126.52	$126.50	$126.50
Purchase #2	$133.94	6.540%	$142.6997	$142.70	$142.70	$142.70
Purchase #3	$140.78	11.302%	$156.691	$156.69	$156.70	$156.70
Purchase #4	$147.71	13.259%	$167.2949	$167.29	$167.30	$167.30
Purchase #5	$186.25	11.567%	$207.7935	$207.79	$207.80	$207.80
Purchase #6	$155.59	4.153%	$162.0517	$162.05	$162.05	$162.10
Purchase #7	$185.82	10.465%	$205.2661	$205.27	$205.25	$205.30
7 purchase totals =	$1,061.67		$1,168.3163	$1,168.31	$1,168.30	$1,168.40