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	$62.64	4.696%	$65.5816	$65.58	$65.60	$65.60
Purchase #2	$110.66	7.785%	$119.2749	$119.27	$119.25	$119.30
Purchase #3	$143.99	12.744%	$162.3401	$162.34	$162.35	$162.30
Purchase #4	$174.54	3.372%	$180.4255	$180.43	$180.45	$180.40
Purchase #5	$173.62	13.332%	$196.767	$196.77	$196.75	$196.80
Purchase #6	$156.94	9.862%	$172.4174	$172.42	$172.40	$172.40
Purchase #7	$119.98	5.699%	$126.8177	$126.82	$126.80	$126.80
7 purchase totals =	$942.37		$1,023.6242	$1,023.63	$1,023.60	$1,023.60