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	$213.68	9.435%	$233.8407	$233.84	$233.85	$233.80
Purchase #2	$203.51	8.285%	$220.3708	$220.37	$220.35	$220.40
Purchase #3	$151.83	8.473%	$164.6946	$164.69	$164.70	$164.70
Purchase #4	$101.93	9.799%	$111.9181	$111.92	$111.90	$111.90
Purchase #5	$173.58	5.240%	$182.6756	$182.68	$182.70	$182.70
Purchase #6	$76.69	11.443%	$85.4656	$85.47	$85.45	$85.50
Purchase #7	$112.64	13.131%	$127.4308	$127.43	$127.45	$127.40
7 purchase totals =	$1,033.86		$1,126.3962	$1,126.40	$1,126.40	$1,126.40