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	$194.44	5.508%	$205.1498	$205.15	$205.15	$205.10
Purchase #2	$96.41	12.663%	$108.6184	$108.62	$108.60	$108.60
Purchase #3	$222.47	8.128%	$240.5524	$240.55	$240.55	$240.60
Purchase #4	$48.34	4.463%	$50.4974	$50.50	$50.50	$50.50
Purchase #5	$116.99	5.339%	$123.2361	$123.24	$123.25	$123.20
Purchase #6	$185.39	5.852%	$196.239	$196.24	$196.25	$196.20
Purchase #7	$80.38	8.589%	$87.2838	$87.28	$87.30	$87.30
7 purchase totals =	$944.42		$1,011.5769	$1,011.58	$1,011.60	$1,011.50