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	$236.35	10.713%	$261.6702	$261.67	$261.65	$261.70
Purchase #2	$141.61	6.371%	$150.632	$150.63	$150.65	$150.60
Purchase #3	$69.76	5.801%	$73.8068	$73.81	$73.80	$73.80
Purchase #4	$166.72	7.392%	$179.0439	$179.04	$179.05	$179.00
Purchase #5	$43.46	4.768%	$45.5322	$45.53	$45.55	$45.50
Purchase #6	$215.92	7.220%	$231.5094	$231.51	$231.50	$231.50
Purchase #7	$195.60	12.693%	$220.4275	$220.43	$220.45	$220.40
7 purchase totals =	$1,069.42		$1,162.6220	$1,162.62	$1,162.65	$1,162.50