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	$173.85	4.755%	$182.1166	$182.12	$182.10	$182.10
Purchase #2	$96.41	8.391%	$104.4998	$104.50	$104.50	$104.50
Purchase #3	$203.78	8.761%	$221.6332	$221.63	$221.65	$221.60
Purchase #4	$241.60	3.661%	$250.445	$250.45	$250.45	$250.40
Purchase #5	$166.43	4.250%	$173.5033	$173.50	$173.50	$173.50
Purchase #6	$118.68	4.857%	$124.4443	$124.44	$124.45	$124.40
Purchase #7	$6.87	7.606%	$7.3925	$7.39	$7.40	$7.40
7 purchase totals =	$1,007.62		$1,064.0347	$1,064.03	$1,064.05	$1,063.90