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	$167.46	13.500%	$190.0671	$190.07	$190.05	$190.10
Purchase #2	$69.87	4.231%	$72.8262	$72.83	$72.85	$72.80
Purchase #3	$12.98	4.180%	$13.5226	$13.52	$13.50	$13.50
Purchase #4	$54.48	7.472%	$58.5507	$58.55	$58.55	$58.60
Purchase #5	$112.66	11.518%	$125.6362	$125.64	$125.65	$125.60
Purchase #6	$72.49	11.364%	$80.7278	$80.73	$80.75	$80.70
Purchase #7	$144.50	12.434%	$162.4671	$162.47	$162.45	$162.50
7 purchase totals =	$634.44		$703.7977	$703.81	$703.80	$703.80