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	$179.89	5.807%	$190.3362	$190.34	$190.35	$190.30
Purchase #2	$175.68	5.273%	$184.9436	$184.94	$184.95	$184.90
Purchase #3	$107.65	4.674%	$112.6816	$112.68	$112.70	$112.70
Purchase #4	$171.63	7.151%	$183.9033	$183.90	$183.90	$183.90
Purchase #5	$35.33	3.338%	$36.5093	$36.51	$36.50	$36.50
Purchase #6	$190.65	5.402%	$200.9489	$200.95	$200.95	$200.90
Purchase #7	$95.62	5.152%	$100.5463	$100.55	$100.55	$100.50
7 purchase totals =	$956.45		$1,009.8692	$1,009.87	$1,009.90	$1,009.70