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	$130.81	9.739%	$143.5496	$143.55	$143.55	$143.50
Purchase #2	$248.73	5.168%	$261.5844	$261.58	$261.60	$261.60
Purchase #3	$182.82	8.522%	$198.3999	$198.40	$198.40	$198.40
Purchase #4	$158.42	4.317%	$165.259	$165.26	$165.25	$165.30
Purchase #5	$207.41	4.576%	$216.9011	$216.90	$216.90	$216.90
Purchase #6	$142.73	11.557%	$159.2253	$159.23	$159.25	$159.20
Purchase #7	$34.41	7.766%	$37.0823	$37.08	$37.10	$37.10
7 purchase totals =	$1,105.33		$1,182.0016	$1,182.00	$1,182.05	$1,182.00