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	$194.75	7.426%	$209.2121	$209.21	$209.20	$209.20
Purchase #2	$67.89	11.835%	$75.9248	$75.92	$75.90	$75.90
Purchase #3	$137.30	10.631%	$151.8964	$151.90	$151.90	$151.90
Purchase #4	$229.80	13.262%	$260.2761	$260.28	$260.30	$260.30
Purchase #5	$169.25	4.312%	$176.5481	$176.55	$176.55	$176.50
Purchase #6	$83.77	4.783%	$87.7767	$87.78	$87.80	$87.80
Purchase #7	$109.53	12.644%	$123.379	$123.38	$123.40	$123.40
7 purchase totals =	$992.29		$1,085.0132	$1,085.02	$1,085.05	$1,085.00