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	$186.94	4.656%	$195.6439	$195.64	$195.65	$195.60
Purchase #2	$184.59	12.699%	$208.0311	$208.03	$208.05	$208.00
Purchase #3	$162.27	5.410%	$171.0488	$171.05	$171.05	$171.00
Purchase #4	$81.41	10.416%	$89.8897	$89.89	$89.90	$89.90
Purchase #5	$117.47	12.696%	$132.384	$132.38	$132.40	$132.40
Purchase #6	$218.88	6.704%	$233.5537	$233.55	$233.55	$233.60
Purchase #7	$231.83	6.294%	$246.4214	$246.42	$246.40	$246.40
7 purchase totals =	$1,183.39		$1,276.9726	$1,276.96	$1,277.00	$1,276.90