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	$92.93	4.299%	$96.9251	$96.93	$96.95	$96.90
Purchase #2	$86.95	13.387%	$98.59	$98.59	$98.60	$98.60
Purchase #3	$190.43	12.484%	$214.2033	$214.20	$214.20	$214.20
Purchase #4	$64.34	5.601%	$67.9437	$67.94	$67.95	$67.90
Purchase #5	$70.82	3.845%	$73.543	$73.54	$73.55	$73.50
Purchase #6	$62.52	4.461%	$65.309	$65.31	$65.30	$65.30
Purchase #7	$59.28	4.676%	$62.0519	$62.05	$62.05	$62.10
7 purchase totals =	$627.27		$678.5660	$678.56	$678.60	$678.50