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	$192.29	11.245%	$213.913	$213.91	$213.90	$213.90
Purchase #2	$155.29	8.151%	$167.9477	$167.95	$167.95	$167.90
Purchase #3	$48.97	13.193%	$55.4306	$55.43	$55.45	$55.40
Purchase #4	$139.98	7.383%	$150.3147	$150.31	$150.30	$150.30
Purchase #5	$222.67	9.702%	$244.2734	$244.27	$244.25	$244.30
Purchase #6	$6.45	9.670%	$7.0737	$7.07	$7.05	$7.10
Purchase #7	$212.38	11.567%	$236.946	$236.95	$236.95	$236.90
7 purchase totals =	$978.03		$1,075.8991	$1,075.89	$1,075.85	$1,075.80