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	$182.69	12.473%	$205.4769	$205.48	$205.50	$205.50
Purchase #2	$115.96	7.411%	$124.5538	$124.55	$124.55	$124.60
Purchase #3	$127.57	12.496%	$143.5111	$143.51	$143.50	$143.50
Purchase #4	$99.75	10.147%	$109.8716	$109.87	$109.85	$109.90
Purchase #5	$247.39	3.274%	$255.4895	$255.49	$255.50	$255.50
Purchase #6	$64.53	3.795%	$66.9789	$66.98	$67.00	$67.00
Purchase #7	$167.52	12.843%	$189.0346	$189.03	$189.05	$189.00
7 purchase totals =	$1,005.41		$1,094.9164	$1,094.91	$1,094.95	$1,095.00