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	$161.69	7.515%	$173.841	$173.84	$173.85	$173.80
Purchase #2	$20.48	6.294%	$21.769	$21.77	$21.75	$21.80
Purchase #3	$5.97	13.296%	$6.7638	$6.76	$6.75	$6.80
Purchase #4	$107.69	9.569%	$117.9949	$117.99	$118.00	$118.00
Purchase #5	$49.72	10.655%	$55.0177	$55.02	$55.00	$55.00
Purchase #6	$56.80	4.849%	$59.5542	$59.55	$59.55	$59.60
Purchase #7	$132.81	13.330%	$150.5136	$150.51	$150.50	$150.50
7 purchase totals =	$535.16		$585.4542	$585.44	$585.40	$585.50