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	$114.48	3.475%	$118.4582	$118.46	$118.45	$118.50
Purchase #2	$214.45	13.281%	$242.9311	$242.93	$242.95	$242.90
Purchase #3	$153.54	9.167%	$167.615	$167.62	$167.60	$167.60
Purchase #4	$185.72	12.119%	$208.2274	$208.23	$208.25	$208.20
Purchase #5	$100.48	5.829%	$106.337	$106.34	$106.35	$106.30
Purchase #6	$151.40	6.242%	$160.8504	$160.85	$160.85	$160.90
Purchase #7	$173.31	4.216%	$180.6167	$180.62	$180.60	$180.60
7 purchase totals =	$1,093.38		$1,185.0358	$1,185.05	$1,185.05	$1,185.00