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	$188.91	8.521%	$205.007	$205.01	$205.00	$205.00
Purchase #2	$133.60	8.868%	$145.4476	$145.45	$145.45	$145.40
Purchase #3	$176.68	13.364%	$200.2915	$200.29	$200.30	$200.30
Purchase #4	$111.89	10.633%	$123.7873	$123.79	$123.80	$123.80
Purchase #5	$125.76	3.475%	$130.1302	$130.13	$130.15	$130.10
Purchase #6	$108.45	11.427%	$120.8426	$120.84	$120.85	$120.80
Purchase #7	$91.40	5.618%	$96.5349	$96.53	$96.55	$96.50
7 purchase totals =	$936.69		$1,022.0411	$1,022.04	$1,022.10	$1,021.90