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	$189.48	3.679%	$196.451	$196.45	$196.45	$196.50
Purchase #2	$10.59	3.790%	$10.9914	$10.99	$11.00	$11.00
Purchase #3	$67.86	12.561%	$76.3839	$76.38	$76.40	$76.40
Purchase #4	$236.38	9.838%	$259.6351	$259.64	$259.65	$259.60
Purchase #5	$188.84	11.500%	$210.5566	$210.56	$210.55	$210.60
Purchase #6	$84.54	5.801%	$89.4442	$89.44	$89.45	$89.40
Purchase #7	$32.28	11.789%	$36.0855	$36.09	$36.10	$36.10
7 purchase totals =	$809.97		$879.5477	$879.55	$879.60	$879.60