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	$59.62	4.492%	$62.2981	$62.30	$62.30	$62.30
Purchase #2	$48.92	4.845%	$51.2902	$51.29	$51.30	$51.30
Purchase #3	$152.80	6.486%	$162.7106	$162.71	$162.70	$162.70
Purchase #4	$42.64	6.128%	$45.253	$45.25	$45.25	$45.30
Purchase #5	$93.35	11.376%	$103.9695	$103.97	$103.95	$104.00
Purchase #6	$99.57	4.321%	$103.8724	$103.87	$103.85	$103.90
Purchase #7	$197.39	3.570%	$204.4368	$204.44	$204.45	$204.40
7 purchase totals =	$694.29		$733.8306	$733.83	$733.80	$733.90