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	$191.73	11.258%	$213.315	$213.32	$213.30	$213.30
Purchase #2	$42.71	7.543%	$45.9316	$45.93	$45.95	$45.90
Purchase #3	$128.90	9.296%	$140.8825	$140.88	$140.90	$140.90
Purchase #4	$78.76	11.545%	$87.8528	$87.85	$87.85	$87.90
Purchase #5	$138.94	13.614%	$157.8553	$157.86	$157.85	$157.90
Purchase #6	$184.67	3.704%	$191.5102	$191.51	$191.50	$191.50
Purchase #7	$119.68	5.681%	$126.479	$126.48	$126.50	$126.50
7 purchase totals =	$885.39		$963.8264	$963.83	$963.85	$963.90