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	$137.99	10.132%	$151.9711	$151.97	$151.95	$152.00
Purchase #2	$177.54	5.864%	$187.9509	$187.95	$187.95	$188.00
Purchase #3	$76.87	9.131%	$83.889	$83.89	$83.90	$83.90
Purchase #4	$162.59	9.743%	$178.4311	$178.43	$178.45	$178.40
Purchase #5	$151.76	8.365%	$164.4547	$164.45	$164.45	$164.50
Purchase #6	$24.75	12.602%	$27.869	$27.87	$27.85	$27.90
Purchase #7	$248.62	9.709%	$272.7585	$272.76	$272.75	$272.80
7 purchase totals =	$980.12		$1,067.3243	$1,067.32	$1,067.30	$1,067.50