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	$191.98	3.599%	$198.8894	$198.89	$198.90	$198.90
Purchase #2	$51.51	13.385%	$58.4046	$58.40	$58.40	$58.40
Purchase #3	$32.92	6.390%	$35.0236	$35.02	$35.00	$35.00
Purchase #4	$12.30	6.372%	$13.0838	$13.08	$13.10	$13.10
Purchase #5	$93.49	7.735%	$100.7215	$100.72	$100.70	$100.70
Purchase #6	$19.77	8.551%	$21.4605	$21.46	$21.45	$21.50
Purchase #7	$36.27	3.429%	$37.5137	$37.51	$37.50	$37.50
7 purchase totals =	$438.24		$465.0971	$465.08	$465.05	$465.10