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	$175.46	12.121%	$196.7275	$196.73	$196.75	$196.70
Purchase #2	$137.64	3.377%	$142.2881	$142.29	$142.30	$142.30
Purchase #3	$224.72	11.562%	$250.7021	$250.70	$250.70	$250.70
Purchase #4	$194.73	11.240%	$216.6177	$216.62	$216.60	$216.60
Purchase #5	$45.29	4.359%	$47.2642	$47.26	$47.25	$47.30
Purchase #6	$112.27	4.545%	$117.3727	$117.37	$117.35	$117.40
Purchase #7	$32.71	4.144%	$34.0655	$34.07	$34.05	$34.10
7 purchase totals =	$922.82		$1,005.0378	$1,005.04	$1,005.00	$1,005.10