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	$196.63	8.532%	$213.4065	$213.41	$213.40	$213.40
Purchase #2	$25.86	11.271%	$28.7747	$28.77	$28.75	$28.80
Purchase #3	$42.39	6.220%	$45.0267	$45.03	$45.05	$45.00
Purchase #4	$123.94	3.727%	$128.5592	$128.56	$128.55	$128.60
Purchase #5	$131.87	11.720%	$147.3252	$147.33	$147.35	$147.30
Purchase #6	$75.56	3.240%	$78.0081	$78.01	$78.00	$78.00
Purchase #7	$43.63	12.159%	$48.935	$48.94	$48.95	$48.90
7 purchase totals =	$639.88		$690.0354	$690.05	$690.05	$690.00