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	$208.89	5.614%	$220.6171	$220.62	$220.60	$220.60
Purchase #2	$100.29	7.186%	$107.4968	$107.50	$107.50	$107.50
Purchase #3	$29.97	6.336%	$31.8689	$31.87	$31.85	$31.90
Purchase #4	$230.87	8.243%	$249.9006	$249.90	$249.90	$249.90
Purchase #5	$250.89	9.732%	$275.3066	$275.31	$275.30	$275.30
Purchase #6	$43.60	5.391%	$45.9505	$45.95	$45.95	$46.00
Purchase #7	$64.91	11.358%	$72.2825	$72.28	$72.30	$72.30
7 purchase totals =	$929.42		$1,003.4230	$1,003.43	$1,003.40	$1,003.50