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	$153.59	7.143%	$164.5609	$164.56	$164.55	$164.60
Purchase #2	$65.34	12.668%	$73.6173	$73.62	$73.60	$73.60
Purchase #3	$241.69	5.672%	$255.3987	$255.40	$255.40	$255.40
Purchase #4	$107.98	4.858%	$113.2257	$113.23	$113.25	$113.20
Purchase #5	$242.96	3.350%	$251.0992	$251.10	$251.10	$251.10
Purchase #6	$33.85	3.287%	$34.9626	$34.96	$34.95	$35.00
Purchase #7	$57.48	4.133%	$59.8556	$59.86	$59.85	$59.90
7 purchase totals =	$902.89		$952.7200	$952.73	$952.70	$952.80