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	$148.53	5.469%	$156.6531	$156.65	$156.65	$156.70
Purchase #2	$113.29	10.130%	$124.7663	$124.77	$124.75	$124.80
Purchase #3	$54.49	4.747%	$57.0766	$57.08	$57.10	$57.10
Purchase #4	$43.33	4.754%	$45.3899	$45.39	$45.40	$45.40
Purchase #5	$117.57	6.512%	$125.2262	$125.23	$125.25	$125.20
Purchase #6	$146.60	4.233%	$152.8056	$152.81	$152.80	$152.80
Purchase #7	$137.28	11.110%	$152.5318	$152.53	$152.55	$152.50
7 purchase totals =	$761.09		$814.4495	$814.46	$814.50	$814.50