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	$108.28	4.604%	$113.2652	$113.27	$113.25	$113.30
Purchase #2	$94.92	4.717%	$99.3974	$99.40	$99.40	$99.40
Purchase #3	$54.36	12.377%	$61.0881	$61.09	$61.10	$61.10
Purchase #4	$105.34	3.372%	$108.8921	$108.89	$108.90	$108.90
Purchase #5	$42.77	10.570%	$47.2908	$47.29	$47.30	$47.30
Purchase #6	$183.39	8.721%	$199.3834	$199.38	$199.40	$199.40
Purchase #7	$90.73	5.221%	$95.467	$95.47	$95.45	$95.50
7 purchase totals =	$679.79		$724.7840	$724.79	$724.80	$724.90