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	$70.88	7.559%	$76.2378	$76.24	$76.25	$76.20
Purchase #2	$90.56	11.186%	$100.69	$100.69	$100.70	$100.70
Purchase #3	$39.47	3.649%	$40.9103	$40.91	$40.90	$40.90
Purchase #4	$21.89	12.534%	$24.6337	$24.63	$24.65	$24.60
Purchase #5	$33.48	3.467%	$34.6408	$34.64	$34.65	$34.60
Purchase #6	$168.76	4.660%	$176.6242	$176.62	$176.60	$176.60
Purchase #7	$146.40	13.359%	$165.9576	$165.96	$165.95	$166.00
7 purchase totals =	$571.44		$619.6944	$619.69	$619.70	$619.60