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	$248.48	7.665%	$267.526	$267.53	$267.55	$267.50
Purchase #2	$41.65	7.778%	$44.8895	$44.89	$44.90	$44.90
Purchase #3	$23.83	8.799%	$25.9268	$25.93	$25.95	$25.90
Purchase #4	$39.99	5.763%	$42.2946	$42.29	$42.30	$42.30
Purchase #5	$82.33	5.632%	$86.9668	$86.97	$86.95	$87.00
Purchase #6	$74.71	5.274%	$78.6502	$78.65	$78.65	$78.70
Purchase #7	$137.53	12.784%	$155.1118	$155.11	$155.10	$155.10
7 purchase totals =	$648.52		$701.3657	$701.37	$701.40	$701.40