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	$58.30	9.570%	$63.8793	$63.88	$63.90	$63.90
Purchase #2	$7.62	5.542%	$8.0423	$8.04	$8.05	$8.00
Purchase #3	$146.32	4.239%	$152.5225	$152.52	$152.50	$152.50
Purchase #4	$205.99	3.193%	$212.5673	$212.57	$212.55	$212.60
Purchase #5	$243.39	11.709%	$271.8885	$271.89	$271.90	$271.90
Purchase #6	$116.79	12.253%	$131.1003	$131.10	$131.10	$131.10
Purchase #7	$185.42	13.523%	$210.4943	$210.49	$210.50	$210.50
7 purchase totals =	$963.83		$1,050.4945	$1,050.49	$1,050.50	$1,050.50