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	$217.42	3.607%	$225.2623	$225.26	$225.25	$225.30
Purchase #2	$15.58	6.747%	$16.6312	$16.63	$16.65	$16.60
Purchase #3	$200.77	5.699%	$212.2119	$212.21	$212.20	$212.20
Purchase #4	$169.83	6.764%	$181.3173	$181.32	$181.30	$181.30
Purchase #5	$237.55	13.842%	$270.4317	$270.43	$270.45	$270.40
Purchase #6	$212.72	3.199%	$219.5249	$219.52	$219.50	$219.50
Purchase #7	$82.42	9.830%	$90.5219	$90.52	$90.50	$90.50
7 purchase totals =	$1,136.29		$1,215.9012	$1,215.89	$1,215.85	$1,215.80