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	$195.91	11.450%	$218.3417	$218.34	$218.35	$218.30
Purchase #2	$191.86	8.690%	$208.5326	$208.53	$208.55	$208.50
Purchase #3	$46.42	8.448%	$50.3416	$50.34	$50.35	$50.30
Purchase #4	$86.45	4.184%	$90.0671	$90.07	$90.05	$90.10
Purchase #5	$230.91	9.373%	$252.5532	$252.55	$252.55	$252.60
Purchase #6	$84.82	6.194%	$90.0738	$90.07	$90.05	$90.10
Purchase #7	$134.98	11.390%	$150.3542	$150.35	$150.35	$150.40
7 purchase totals =	$971.35		$1,060.2642	$1,060.25	$1,060.25	$1,060.30