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	$103.64	12.389%	$116.48	$116.48	$116.50	$116.50
Purchase #2	$22.51	13.444%	$25.5362	$25.54	$25.55	$25.50
Purchase #3	$200.62	4.148%	$208.9417	$208.94	$208.95	$208.90
Purchase #4	$29.32	12.346%	$32.9398	$32.94	$32.95	$32.90
Purchase #5	$216.27	9.366%	$236.5258	$236.53	$236.55	$236.50
Purchase #6	$152.25	10.771%	$168.6488	$168.65	$168.65	$168.60
Purchase #7	$243.27	6.656%	$259.4621	$259.46	$259.45	$259.50
7 purchase totals =	$967.88		$1,048.5344	$1,048.54	$1,048.60	$1,048.40