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	$153.28	7.828%	$165.2788	$165.28	$165.30	$165.30
Purchase #2	$188.25	7.481%	$202.333	$202.33	$202.35	$202.30
Purchase #3	$250.89	11.312%	$279.2707	$279.27	$279.25	$279.30
Purchase #4	$47.97	7.342%	$51.492	$51.49	$51.50	$51.50
Purchase #5	$228.53	13.352%	$259.0433	$259.04	$259.05	$259.00
Purchase #6	$44.33	3.274%	$45.7814	$45.78	$45.80	$45.80
Purchase #7	$187.85	3.110%	$193.6921	$193.69	$193.70	$193.70
7 purchase totals =	$1,101.10		$1,196.8913	$1,196.88	$1,196.95	$1,196.90