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	$196.41	4.841%	$205.9182	$205.92	$205.90	$205.90
Purchase #2	$196.77	11.697%	$219.7862	$219.79	$219.80	$219.80
Purchase #3	$116.29	13.207%	$131.6484	$131.65	$131.65	$131.60
Purchase #4	$31.27	13.311%	$35.4323	$35.43	$35.45	$35.40
Purchase #5	$171.60	9.842%	$188.4889	$188.49	$188.50	$188.50
Purchase #6	$121.25	6.387%	$128.9942	$128.99	$129.00	$129.00
Purchase #7	$175.85	11.462%	$196.0059	$196.01	$196.00	$196.00
7 purchase totals =	$1,009.44		$1,106.2741	$1,106.28	$1,106.30	$1,106.20