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	$168.43	11.340%	$187.53	$187.53	$187.55	$187.50
Purchase #2	$112.46	3.375%	$116.2555	$116.26	$116.25	$116.30
Purchase #3	$215.53	6.450%	$229.4317	$229.43	$229.45	$229.40
Purchase #4	$161.32	4.725%	$168.9424	$168.94	$168.95	$168.90
Purchase #5	$174.74	3.575%	$180.987	$180.99	$181.00	$181.00
Purchase #6	$150.94	11.707%	$168.6105	$168.61	$168.60	$168.60
Purchase #7	$48.93	11.664%	$54.6372	$54.64	$54.65	$54.60
7 purchase totals =	$1,032.35		$1,106.3943	$1,106.40	$1,106.45	$1,106.30