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	$201.47	10.725%	$223.0777	$223.08	$223.10	$223.10
Purchase #2	$191.34	13.685%	$217.5249	$217.52	$217.50	$217.50
Purchase #3	$78.31	6.750%	$83.5959	$83.60	$83.60	$83.60
Purchase #4	$126.97	13.730%	$144.403	$144.40	$144.40	$144.40
Purchase #5	$156.92	8.473%	$170.2158	$170.22	$170.20	$170.20
Purchase #6	$91.45	12.830%	$103.183	$103.18	$103.20	$103.20
Purchase #7	$96.50	5.589%	$101.8934	$101.89	$101.90	$101.90
7 purchase totals =	$942.96		$1,043.8937	$1,043.89	$1,043.90	$1,043.90