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	$108.57	4.664%	$113.6337	$113.63	$113.65	$113.60
Purchase #2	$7.64	11.665%	$8.5312	$8.53	$8.55	$8.50
Purchase #3	$5.27	4.647%	$5.5149	$5.51	$5.50	$5.50
Purchase #4	$24.89	9.229%	$27.1871	$27.19	$27.20	$27.20
Purchase #5	$76.95	11.181%	$85.5538	$85.55	$85.55	$85.60
Purchase #6	$116.72	9.614%	$127.9415	$127.94	$127.95	$127.90
Purchase #7	$229.67	10.267%	$253.2502	$253.25	$253.25	$253.30
7 purchase totals =	$569.71		$621.6124	$621.60	$621.65	$621.60