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	$78.44	9.707%	$86.0542	$86.05	$86.05	$86.10
Purchase #2	$176.93	10.508%	$195.5218	$195.52	$195.50	$195.50
Purchase #3	$191.65	8.134%	$207.2388	$207.24	$207.25	$207.20
Purchase #4	$245.58	7.573%	$264.1778	$264.18	$264.20	$264.20
Purchase #5	$34.34	7.761%	$37.0051	$37.01	$37.00	$37.00
Purchase #6	$56.90	4.464%	$59.44	$59.44	$59.45	$59.40
Purchase #7	$165.60	4.523%	$173.0901	$173.09	$173.10	$173.10
7 purchase totals =	$949.44		$1,022.5278	$1,022.53	$1,022.55	$1,022.50