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	$196.92	3.669%	$204.145	$204.15	$204.15	$204.10
Purchase #2	$29.51	7.816%	$31.8165	$31.82	$31.80	$31.80
Purchase #3	$41.45	9.190%	$45.2593	$45.26	$45.25	$45.30
Purchase #4	$192.73	11.337%	$214.5798	$214.58	$214.60	$214.60
Purchase #5	$109.78	6.553%	$116.9739	$116.97	$116.95	$117.00
Purchase #6	$181.96	8.147%	$196.7843	$196.78	$196.80	$196.80
Purchase #7	$200.36	5.563%	$211.506	$211.51	$211.50	$211.50
7 purchase totals =	$952.71		$1,021.0648	$1,021.07	$1,021.05	$1,021.10