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	$151.25	8.477%	$164.0715	$164.07	$164.05	$164.10
Purchase #2	$96.52	5.180%	$101.5197	$101.52	$101.50	$101.50
Purchase #3	$194.86	10.752%	$215.8113	$215.81	$215.80	$215.80
Purchase #4	$201.77	10.184%	$222.3183	$222.32	$222.30	$222.30
Purchase #5	$98.28	13.362%	$111.4122	$111.41	$111.40	$111.40
Purchase #6	$104.39	3.494%	$108.0374	$108.04	$108.05	$108.00
Purchase #7	$109.42	3.419%	$113.1611	$113.16	$113.15	$113.20
7 purchase totals =	$956.49		$1,036.3315	$1,036.33	$1,036.25	$1,036.30