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	$141.35	8.561%	$153.451	$153.45	$153.45	$153.50
Purchase #2	$187.39	6.809%	$200.1494	$200.15	$200.15	$200.10
Purchase #3	$134.38	13.297%	$152.2485	$152.25	$152.25	$152.20
Purchase #4	$84.40	11.518%	$94.1212	$94.12	$94.10	$94.10
Purchase #5	$107.30	11.213%	$119.3315	$119.33	$119.35	$119.30
Purchase #6	$203.59	11.871%	$227.7582	$227.76	$227.75	$227.80
Purchase #7	$105.39	6.315%	$112.0454	$112.05	$112.05	$112.00
7 purchase totals =	$963.80		$1,059.1052	$1,059.11	$1,059.10	$1,059.00