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	$184.95	13.257%	$209.4688	$209.47	$209.45	$209.50
Purchase #2	$164.64	12.670%	$185.4999	$185.50	$185.50	$185.50
Purchase #3	$211.83	4.864%	$222.1334	$222.13	$222.15	$222.10
Purchase #4	$82.65	8.571%	$89.7339	$89.73	$89.75	$89.70
Purchase #5	$62.39	8.321%	$67.5815	$67.58	$67.60	$67.60
Purchase #6	$10.35	10.542%	$11.4411	$11.44	$11.45	$11.40
Purchase #7	$159.92	11.463%	$178.2516	$178.25	$178.25	$178.30
7 purchase totals =	$876.73		$964.1102	$964.10	$964.15	$964.10