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	$241.81	11.600%	$269.86	$269.86	$269.85	$269.90
Purchase #2	$69.88	4.140%	$72.773	$72.77	$72.75	$72.80
Purchase #3	$60.66	8.465%	$65.7949	$65.79	$65.80	$65.80
Purchase #4	$55.56	6.582%	$59.217	$59.22	$59.20	$59.20
Purchase #5	$231.40	3.419%	$239.3116	$239.31	$239.30	$239.30
Purchase #6	$184.84	6.265%	$196.4202	$196.42	$196.40	$196.40
Purchase #7	$112.44	11.296%	$125.1412	$125.14	$125.15	$125.10
7 purchase totals =	$956.59		$1,028.5179	$1,028.51	$1,028.45	$1,028.50