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	$197.43	9.162%	$215.5185	$215.52	$215.50	$215.50
Purchase #2	$172.96	4.264%	$180.335	$180.34	$180.35	$180.30
Purchase #3	$81.31	6.779%	$86.822	$86.82	$86.80	$86.80
Purchase #4	$137.59	6.671%	$146.7686	$146.77	$146.75	$146.80
Purchase #5	$200.97	12.372%	$225.834	$225.83	$225.85	$225.80
Purchase #6	$73.84	8.184%	$79.8831	$79.88	$79.90	$79.90
Purchase #7	$96.68	5.385%	$101.8862	$101.89	$101.90	$101.90
7 purchase totals =	$960.78		$1,037.0474	$1,037.05	$1,037.05	$1,037.00