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	$213.41	10.555%	$235.9354	$235.94	$235.95	$235.90
Purchase #2	$193.37	13.845%	$220.1421	$220.14	$220.15	$220.10
Purchase #3	$182.86	13.828%	$208.1459	$208.15	$208.15	$208.10
Purchase #4	$138.83	9.619%	$152.1841	$152.18	$152.20	$152.20
Purchase #5	$33.40	12.341%	$37.5219	$37.52	$37.50	$37.50
Purchase #6	$156.52	9.292%	$171.0638	$171.06	$171.05	$171.10
Purchase #7	$170.93	8.292%	$185.1035	$185.10	$185.10	$185.10
7 purchase totals =	$1,089.32		$1,210.0967	$1,210.09	$1,210.10	$1,210.00