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	$216.39	4.445%	$226.0085	$226.01	$226.00	$226.00
Purchase #2	$42.39	3.614%	$43.922	$43.92	$43.90	$43.90
Purchase #3	$48.37	5.435%	$50.9989	$51.00	$51.00	$51.00
Purchase #4	$235.43	10.831%	$260.9294	$260.93	$260.95	$260.90
Purchase #5	$130.53	6.690%	$139.2625	$139.26	$139.25	$139.30
Purchase #6	$176.86	7.711%	$190.4977	$190.50	$190.50	$190.50
Purchase #7	$170.92	12.180%	$191.7381	$191.74	$191.75	$191.70
7 purchase totals =	$1,020.89		$1,103.3571	$1,103.36	$1,103.35	$1,103.30