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	$200.54	8.366%	$217.3172	$217.32	$217.30	$217.30
Purchase #2	$34.87	10.307%	$38.4641	$38.46	$38.45	$38.50
Purchase #3	$233.44	3.397%	$241.37	$241.37	$241.35	$241.40
Purchase #4	$41.69	4.551%	$43.5873	$43.59	$43.60	$43.60
Purchase #5	$237.71	13.704%	$270.2858	$270.29	$270.30	$270.30
Purchase #6	$180.67	5.838%	$191.2175	$191.22	$191.20	$191.20
Purchase #7	$97.56	6.190%	$103.599	$103.60	$103.60	$103.60
7 purchase totals =	$1,026.48		$1,105.8409	$1,105.85	$1,105.80	$1,105.90