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	$32.78	9.344%	$35.843	$35.84	$35.85	$35.80
Purchase #2	$43.57	5.210%	$45.84	$45.84	$45.85	$45.80
Purchase #3	$178.65	12.189%	$200.4256	$200.43	$200.45	$200.40
Purchase #4	$47.55	12.441%	$53.4657	$53.47	$53.45	$53.50
Purchase #5	$29.94	6.243%	$31.8092	$31.81	$31.80	$31.80
Purchase #6	$111.92	11.701%	$125.0158	$125.02	$125.00	$125.00
Purchase #7	$225.50	12.781%	$254.3212	$254.32	$254.30	$254.30
7 purchase totals =	$669.91		$746.7205	$746.73	$746.70	$746.60