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	$150.71	11.703%	$168.3476	$168.35	$168.35	$168.30
Purchase #2	$72.93	5.120%	$76.664	$76.66	$76.65	$76.70
Purchase #3	$134.80	8.650%	$146.4602	$146.46	$146.45	$146.50
Purchase #4	$142.71	6.171%	$151.5166	$151.52	$151.50	$151.50
Purchase #5	$161.92	3.478%	$167.5516	$167.55	$167.55	$167.60
Purchase #6	$102.63	11.611%	$114.5464	$114.55	$114.55	$114.50
Purchase #7	$220.42	4.195%	$229.6666	$229.67	$229.65	$229.70
7 purchase totals =	$986.12		$1,054.7530	$1,054.76	$1,054.70	$1,054.80