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	$151.39	9.449%	$165.6948	$165.69	$165.70	$165.70
Purchase #2	$82.47	6.172%	$87.56	$87.56	$87.55	$87.60
Purchase #3	$105.68	5.470%	$111.4607	$111.46	$111.45	$111.50
Purchase #4	$90.93	5.424%	$95.862	$95.86	$95.85	$95.90
Purchase #5	$163.67	4.639%	$171.2627	$171.26	$171.25	$171.30
Purchase #6	$124.30	5.443%	$131.0656	$131.07	$131.05	$131.10
Purchase #7	$227.92	6.804%	$243.4277	$243.43	$243.45	$243.40
7 purchase totals =	$946.36		$1,006.3335	$1,006.33	$1,006.30	$1,006.50