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	$62.35	8.828%	$67.8543	$67.85	$67.85	$67.90
Purchase #2	$127.61	11.175%	$141.8704	$141.87	$141.85	$141.90
Purchase #3	$87.33	5.229%	$91.8965	$91.90	$91.90	$91.90
Purchase #4	$214.72	11.675%	$239.7886	$239.79	$239.80	$239.80
Purchase #5	$55.70	8.256%	$60.2986	$60.30	$60.30	$60.30
Purchase #6	$172.87	9.126%	$188.6461	$188.65	$188.65	$188.60
Purchase #7	$248.28	4.110%	$258.4843	$258.48	$258.50	$258.50
7 purchase totals =	$968.86		$1,048.8388	$1,048.84	$1,048.85	$1,048.90