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	$182.77	7.690%	$196.825	$196.83	$196.85	$196.80
Purchase #2	$180.46	10.595%	$199.5797	$199.58	$199.60	$199.60
Purchase #3	$198.86	9.739%	$218.227	$218.23	$218.25	$218.20
Purchase #4	$119.86	13.545%	$136.095	$136.10	$136.10	$136.10
Purchase #5	$119.71	3.114%	$123.4378	$123.44	$123.45	$123.40
Purchase #6	$27.45	9.178%	$29.9694	$29.97	$29.95	$30.00
Purchase #7	$220.86	3.424%	$228.4222	$228.42	$228.40	$228.40
7 purchase totals =	$1,049.97		$1,132.5561	$1,132.57	$1,132.60	$1,132.50