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	$115.31	9.544%	$126.3152	$126.32	$126.30	$126.30
Purchase #2	$196.53	10.523%	$217.2109	$217.21	$217.20	$217.20
Purchase #3	$31.47	7.792%	$33.9221	$33.92	$33.90	$33.90
Purchase #4	$209.52	9.253%	$228.9069	$228.91	$228.90	$228.90
Purchase #5	$10.62	12.372%	$11.9339	$11.93	$11.95	$11.90
Purchase #6	$219.94	10.643%	$243.3482	$243.35	$243.35	$243.30
Purchase #7	$179.44	11.458%	$200.0002	$200.00	$200.00	$200.00
7 purchase totals =	$962.83		$1,061.6374	$1,061.64	$1,061.60	$1,061.50