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	$196.42	8.836%	$213.7757	$213.78	$213.80	$213.80
Purchase #2	$50.76	11.862%	$56.7812	$56.78	$56.80	$56.80
Purchase #3	$79.31	8.526%	$86.072	$86.07	$86.05	$86.10
Purchase #4	$171.50	12.468%	$192.8826	$192.88	$192.90	$192.90
Purchase #5	$189.80	12.454%	$213.4377	$213.44	$213.45	$213.40
Purchase #6	$187.32	12.363%	$210.4784	$210.48	$210.50	$210.50
Purchase #7	$65.46	12.705%	$73.7767	$73.78	$73.80	$73.80
7 purchase totals =	$940.57		$1,047.2043	$1,047.21	$1,047.30	$1,047.30