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	$86.36	3.800%	$89.6417	$89.64	$89.65	$89.60
Purchase #2	$245.59	8.109%	$265.5049	$265.50	$265.50	$265.50
Purchase #3	$236.96	13.716%	$269.4614	$269.46	$269.45	$269.50
Purchase #4	$30.69	4.552%	$32.087	$32.09	$32.10	$32.10
Purchase #5	$190.97	4.860%	$200.2511	$200.25	$200.25	$200.30
Purchase #6	$95.73	7.555%	$102.9624	$102.96	$102.95	$103.00
Purchase #7	$38.65	7.434%	$41.5232	$41.52	$41.50	$41.50
7 purchase totals =	$924.95		$1,001.4317	$1,001.42	$1,001.40	$1,001.50