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	$211.30	10.532%	$233.5541	$233.55	$233.55	$233.60
Purchase #2	$196.52	3.772%	$203.9327	$203.93	$203.95	$203.90
Purchase #3	$243.97	4.696%	$255.4268	$255.43	$255.45	$255.40
Purchase #4	$208.42	4.863%	$218.5555	$218.56	$218.55	$218.60
Purchase #5	$231.38	10.566%	$255.8276	$255.83	$255.85	$255.80
Purchase #6	$128.44	11.418%	$143.1053	$143.11	$143.10	$143.10
Purchase #7	$163.66	13.483%	$185.7263	$185.73	$185.75	$185.70
7 purchase totals =	$1,383.69		$1,496.1283	$1,496.14	$1,496.20	$1,496.10