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	$114.35	10.390%	$126.231	$126.23	$126.25	$126.20
Purchase #2	$227.30	8.604%	$246.8569	$246.86	$246.85	$246.90
Purchase #3	$152.79	4.792%	$160.1117	$160.11	$160.10	$160.10
Purchase #4	$212.95	8.518%	$231.0891	$231.09	$231.10	$231.10
Purchase #5	$115.42	11.233%	$128.3851	$128.39	$128.40	$128.40
Purchase #6	$71.44	10.321%	$78.8133	$78.81	$78.80	$78.80
Purchase #7	$116.71	6.158%	$123.897	$123.90	$123.90	$123.90
7 purchase totals =	$1,010.96		$1,095.3841	$1,095.39	$1,095.40	$1,095.40