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	$196.53	8.619%	$213.4689	$213.47	$213.45	$213.50
Purchase #2	$29.46	9.661%	$32.3061	$32.31	$32.30	$32.30
Purchase #3	$190.66	4.341%	$198.9366	$198.94	$198.95	$198.90
Purchase #4	$134.91	5.720%	$142.6269	$142.63	$142.65	$142.60
Purchase #5	$173.69	5.124%	$182.5899	$182.59	$182.60	$182.60
Purchase #6	$210.58	7.547%	$226.4725	$226.47	$226.45	$226.50
Purchase #7	$94.25	11.310%	$104.9097	$104.91	$104.90	$104.90
7 purchase totals =	$1,030.08		$1,101.3106	$1,101.32	$1,101.30	$1,101.30