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	$221.41	11.309%	$246.4493	$246.45	$246.45	$246.40
Purchase #2	$44.25	5.784%	$46.8094	$46.81	$46.80	$46.80
Purchase #3	$197.45	6.154%	$209.6011	$209.60	$209.60	$209.60
Purchase #4	$89.57	9.243%	$97.849	$97.85	$97.85	$97.80
Purchase #5	$83.77	6.244%	$89.0006	$89.00	$89.00	$89.00
Purchase #6	$175.62	7.535%	$188.853	$188.85	$188.85	$188.90
Purchase #7	$139.55	5.259%	$146.8889	$146.89	$146.90	$146.90
7 purchase totals =	$951.62		$1,025.4513	$1,025.45	$1,025.45	$1,025.40