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	$176.47	11.395%	$196.5788	$196.58	$196.60	$196.60
Purchase #2	$228.40	9.683%	$250.516	$250.52	$250.50	$250.50
Purchase #3	$90.95	12.115%	$101.9686	$101.97	$101.95	$102.00
Purchase #4	$55.82	4.726%	$58.4581	$58.46	$58.45	$58.50
Purchase #5	$102.55	3.790%	$106.4366	$106.44	$106.45	$106.40
Purchase #6	$58.52	5.821%	$61.9264	$61.93	$61.95	$61.90
Purchase #7	$94.59	7.277%	$101.4733	$101.47	$101.45	$101.50
7 purchase totals =	$807.30		$877.3578	$877.37	$877.35	$877.40