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	$129.96	10.686%	$143.8475	$143.85	$143.85	$143.80
Purchase #2	$237.95	10.337%	$262.5469	$262.55	$262.55	$262.50
Purchase #3	$90.31	13.850%	$102.8179	$102.82	$102.80	$102.80
Purchase #4	$229.31	11.423%	$255.5041	$255.50	$255.50	$255.50
Purchase #5	$20.75	13.556%	$23.5629	$23.56	$23.55	$23.60
Purchase #6	$141.65	3.156%	$146.1205	$146.12	$146.10	$146.10
Purchase #7	$233.38	12.110%	$261.6423	$261.64	$261.65	$261.60
7 purchase totals =	$1,083.31		$1,196.0421	$1,196.04	$1,196.00	$1,195.90