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	$214.81	10.103%	$236.5123	$236.51	$236.50	$236.50
Purchase #2	$57.84	3.500%	$59.8644	$59.86	$59.85	$59.90
Purchase #3	$44.88	10.135%	$49.4286	$49.43	$49.45	$49.40
Purchase #4	$201.25	9.176%	$219.7167	$219.72	$219.70	$219.70
Purchase #5	$213.64	9.352%	$233.6196	$233.62	$233.60	$233.60
Purchase #6	$92.47	3.129%	$95.3634	$95.36	$95.35	$95.40
Purchase #7	$201.55	7.801%	$217.2729	$217.27	$217.25	$217.30
7 purchase totals =	$1,026.44		$1,111.7779	$1,111.77	$1,111.70	$1,111.80