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	$92.54	4.633%	$96.8274	$96.83	$96.85	$96.80
Purchase #2	$12.41	5.247%	$13.0612	$13.06	$13.05	$13.10
Purchase #3	$53.67	7.867%	$57.8922	$57.89	$57.90	$57.90
Purchase #4	$160.57	11.230%	$178.602	$178.60	$178.60	$178.60
Purchase #5	$32.97	7.711%	$35.5123	$35.51	$35.50	$35.50
Purchase #6	$140.37	11.312%	$156.2487	$156.25	$156.25	$156.20
Purchase #7	$64.96	6.347%	$69.083	$69.08	$69.10	$69.10
7 purchase totals =	$557.49		$607.2268	$607.22	$607.25	$607.20