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	$200.44	9.461%	$219.4036	$219.40	$219.40	$219.40
Purchase #2	$51.35	10.289%	$56.6334	$56.63	$56.65	$56.60
Purchase #3	$199.89	13.615%	$227.105	$227.11	$227.10	$227.10
Purchase #4	$109.88	5.176%	$115.5674	$115.57	$115.55	$115.60
Purchase #5	$34.65	3.676%	$35.9237	$35.92	$35.90	$35.90
Purchase #6	$174.53	12.700%	$196.6953	$196.70	$196.70	$196.70
Purchase #7	$226.32	12.484%	$254.5738	$254.57	$254.55	$254.60
7 purchase totals =	$997.06		$1,105.9022	$1,105.90	$1,105.85	$1,105.90