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	$95.91	3.118%	$98.9005	$98.90	$98.90	$98.90
Purchase #2	$102.34	12.139%	$114.7631	$114.76	$114.75	$114.80
Purchase #3	$176.49	10.187%	$194.469	$194.47	$194.45	$194.50
Purchase #4	$184.72	6.322%	$196.398	$196.40	$196.40	$196.40
Purchase #5	$142.91	7.768%	$154.0112	$154.01	$154.00	$154.00
Purchase #6	$105.52	3.730%	$109.4559	$109.46	$109.45	$109.50
Purchase #7	$196.82	8.490%	$213.53	$213.53	$213.55	$213.50
7 purchase totals =	$1,004.71		$1,081.5277	$1,081.53	$1,081.50	$1,081.60