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	$162.49	7.491%	$174.6621	$174.66	$174.65	$174.70
Purchase #2	$64.44	12.243%	$72.3294	$72.33	$72.35	$72.30
Purchase #3	$83.49	8.399%	$90.5023	$90.50	$90.50	$90.50
Purchase #4	$240.32	6.516%	$255.9793	$255.98	$256.00	$256.00
Purchase #5	$217.44	5.610%	$229.6384	$229.64	$229.65	$229.60
Purchase #6	$78.57	10.671%	$86.9542	$86.95	$86.95	$87.00
Purchase #7	$128.77	11.624%	$143.7382	$143.74	$143.75	$143.70
7 purchase totals =	$975.52		$1,053.8039	$1,053.80	$1,053.85	$1,053.80