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	$211.60	5.296%	$222.8063	$222.81	$222.80	$222.80
Purchase #2	$233.43	11.208%	$259.5928	$259.59	$259.60	$259.60
Purchase #3	$80.66	7.513%	$86.72	$86.72	$86.70	$86.70
Purchase #4	$216.38	8.791%	$235.402	$235.40	$235.40	$235.40
Purchase #5	$96.31	5.821%	$101.9162	$101.92	$101.90	$101.90
Purchase #6	$102.39	8.439%	$111.0307	$111.03	$111.05	$111.00
Purchase #7	$14.67	3.153%	$15.1325	$15.13	$15.15	$15.10
7 purchase totals =	$955.44		$1,032.6005	$1,032.60	$1,032.60	$1,032.50