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	$43.86	6.320%	$46.632	$46.63	$46.65	$46.60
Purchase #2	$87.31	13.240%	$98.8698	$98.87	$98.85	$98.90
Purchase #3	$172.85	9.533%	$189.3278	$189.33	$189.35	$189.30
Purchase #4	$237.81	8.713%	$258.5304	$258.53	$258.55	$258.50
Purchase #5	$250.57	8.553%	$272.0013	$272.00	$272.00	$272.00
Purchase #6	$72.51	8.835%	$78.9163	$78.92	$78.90	$78.90
Purchase #7	$207.36	6.759%	$221.3755	$221.38	$221.40	$221.40
7 purchase totals =	$1,072.27		$1,165.6531	$1,165.66	$1,165.70	$1,165.60