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	$145.47	5.151%	$152.9632	$152.96	$152.95	$153.00
Purchase #2	$219.35	5.583%	$231.5963	$231.60	$231.60	$231.60
Purchase #3	$151.79	3.293%	$156.7884	$156.79	$156.80	$156.80
Purchase #4	$47.82	6.420%	$50.89	$50.89	$50.90	$50.90
Purchase #5	$20.40	8.126%	$22.0577	$22.06	$22.05	$22.10
Purchase #6	$196.65	13.484%	$223.1663	$223.17	$223.15	$223.20
Purchase #7	$167.35	8.186%	$181.0493	$181.05	$181.05	$181.00
7 purchase totals =	$948.83		$1,018.5112	$1,018.52	$1,018.50	$1,018.60