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	$185.64	4.796%	$194.5433	$194.54	$194.55	$194.50
Purchase #2	$194.31	9.863%	$213.4748	$213.47	$213.45	$213.50
Purchase #3	$87.37	10.766%	$96.7763	$96.78	$96.80	$96.80
Purchase #4	$178.89	3.371%	$184.9204	$184.92	$184.90	$184.90
Purchase #5	$185.63	12.136%	$208.1581	$208.16	$208.15	$208.20
Purchase #6	$133.81	13.633%	$152.0523	$152.05	$152.05	$152.10
Purchase #7	$172.39	9.306%	$188.4326	$188.43	$188.45	$188.40
7 purchase totals =	$1,138.04		$1,238.3578	$1,238.35	$1,238.35	$1,238.40