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	$181.67	10.427%	$200.6127	$200.61	$200.60	$200.60
Purchase #2	$198.51	5.320%	$209.0707	$209.07	$209.05	$209.10
Purchase #3	$66.77	5.574%	$70.4918	$70.49	$70.50	$70.50
Purchase #4	$199.29	10.680%	$220.5742	$220.57	$220.55	$220.60
Purchase #5	$144.27	12.599%	$162.4466	$162.45	$162.45	$162.40
Purchase #6	$74.94	8.837%	$81.5624	$81.56	$81.55	$81.60
Purchase #7	$119.25	6.800%	$127.359	$127.36	$127.35	$127.40
7 purchase totals =	$984.70		$1,072.1174	$1,072.11	$1,072.05	$1,072.20