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	$44.94	3.328%	$46.4356	$46.44	$46.45	$46.40
Purchase #2	$41.38	3.543%	$42.8461	$42.85	$42.85	$42.80
Purchase #3	$92.31	12.469%	$103.8201	$103.82	$103.80	$103.80
Purchase #4	$29.90	6.288%	$31.7801	$31.78	$31.80	$31.80
Purchase #5	$10.50	4.787%	$11.0026	$11.00	$11.00	$11.00
Purchase #6	$102.83	9.797%	$112.9043	$112.90	$112.90	$112.90
Purchase #7	$29.61	11.335%	$32.9663	$32.97	$32.95	$33.00
7 purchase totals =	$351.47		$381.7551	$381.76	$381.75	$381.70