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	$47.92	11.364%	$53.3656	$53.37	$53.35	$53.40
Purchase #2	$114.31	4.556%	$119.518	$119.52	$119.50	$119.50
Purchase #3	$148.44	11.725%	$165.8446	$165.84	$165.85	$165.80
Purchase #4	$12.67	9.415%	$13.8629	$13.86	$13.85	$13.90
Purchase #5	$168.69	11.147%	$187.4939	$187.49	$187.50	$187.50
Purchase #6	$211.64	9.153%	$231.0114	$231.01	$231.00	$231.00
Purchase #7	$60.31	10.233%	$66.4815	$66.48	$66.50	$66.50
7 purchase totals =	$763.98		$837.5779	$837.57	$837.55	$837.60