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	$195.98	7.349%	$210.3826	$210.38	$210.40	$210.40
Purchase #2	$244.82	6.407%	$260.5056	$260.51	$260.50	$260.50
Purchase #3	$115.79	10.462%	$127.9039	$127.90	$127.90	$127.90
Purchase #4	$185.51	6.367%	$197.3214	$197.32	$197.30	$197.30
Purchase #5	$117.39	6.293%	$124.7774	$124.78	$124.80	$124.80
Purchase #6	$88.55	13.151%	$100.1952	$100.20	$100.20	$100.20
Purchase #7	$19.80	10.356%	$21.8505	$21.85	$21.85	$21.90
7 purchase totals =	$967.84		$1,042.9366	$1,042.94	$1,042.95	$1,043.00