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	$188.54	13.553%	$214.0928	$214.09	$214.10	$214.10
Purchase #2	$41.46	11.847%	$46.3718	$46.37	$46.35	$46.40
Purchase #3	$153.35	7.782%	$165.2837	$165.28	$165.30	$165.30
Purchase #4	$56.88	4.256%	$59.3008	$59.30	$59.30	$59.30
Purchase #5	$109.79	9.201%	$119.8918	$119.89	$119.90	$119.90
Purchase #6	$189.83	10.819%	$210.3677	$210.37	$210.35	$210.40
Purchase #7	$179.87	8.115%	$194.4665	$194.47	$194.45	$194.50
7 purchase totals =	$919.72		$1,009.7751	$1,009.77	$1,009.75	$1,009.90