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	$211.57	13.829%	$240.828	$240.83	$240.85	$240.80
Purchase #2	$171.42	11.690%	$191.459	$191.46	$191.45	$191.50
Purchase #3	$137.31	9.381%	$150.1911	$150.19	$150.20	$150.20
Purchase #4	$96.72	12.736%	$109.0383	$109.04	$109.05	$109.00
Purchase #5	$150.83	4.360%	$157.4062	$157.41	$157.40	$157.40
Purchase #6	$214.51	3.498%	$222.0136	$222.01	$222.00	$222.00
Purchase #7	$248.48	5.545%	$262.2582	$262.26	$262.25	$262.30
7 purchase totals =	$1,230.84		$1,333.1944	$1,333.20	$1,333.20	$1,333.20