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	$188.34	13.345%	$213.474	$213.47	$213.45	$213.50
Purchase #2	$11.72	13.739%	$13.3302	$13.33	$13.35	$13.30
Purchase #3	$164.49	9.478%	$180.0804	$180.08	$180.10	$180.10
Purchase #4	$126.79	12.397%	$142.5082	$142.51	$142.50	$142.50
Purchase #5	$227.67	12.642%	$256.452	$256.45	$256.45	$256.50
Purchase #6	$160.44	5.733%	$169.638	$169.64	$169.65	$169.60
Purchase #7	$184.54	4.313%	$192.4992	$192.50	$192.50	$192.50
7 purchase totals =	$1,063.99		$1,167.9820	$1,167.98	$1,168.00	$1,168.00