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	$76.27	12.268%	$85.6268	$85.63	$85.65	$85.60
Purchase #2	$167.91	8.236%	$181.7391	$181.74	$181.75	$181.70
Purchase #3	$220.35	3.401%	$227.8441	$227.84	$227.85	$227.80
Purchase #4	$65.40	3.435%	$67.6465	$67.65	$67.65	$67.60
Purchase #5	$150.29	13.630%	$170.7745	$170.77	$170.75	$170.80
Purchase #6	$81.83	5.570%	$86.3879	$86.39	$86.40	$86.40
Purchase #7	$214.59	5.268%	$225.8946	$225.89	$225.90	$225.90
7 purchase totals =	$976.64		$1,045.9135	$1,045.91	$1,045.95	$1,045.80