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	$33.82	4.747%	$35.4254	$35.43	$35.45	$35.40
Purchase #2	$107.49	10.104%	$118.3508	$118.35	$118.35	$118.40
Purchase #3	$152.48	9.585%	$167.0952	$167.10	$167.10	$167.10
Purchase #4	$105.52	9.501%	$115.5455	$115.55	$115.55	$115.50
Purchase #5	$208.90	11.278%	$232.4597	$232.46	$232.45	$232.50
Purchase #6	$142.69	8.311%	$154.549	$154.55	$154.55	$154.50
Purchase #7	$213.44	11.628%	$238.2588	$238.26	$238.25	$238.30
7 purchase totals =	$964.34		$1,061.6844	$1,061.70	$1,061.70	$1,061.70