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	$151.85	10.326%	$167.53	$167.53	$167.55	$167.50
Purchase #2	$169.63	4.316%	$176.9512	$176.95	$176.95	$177.00
Purchase #3	$163.77	7.631%	$176.2673	$176.27	$176.25	$176.30
Purchase #4	$94.51	4.824%	$99.0692	$99.07	$99.05	$99.10
Purchase #5	$160.85	9.828%	$176.6583	$176.66	$176.65	$176.70
Purchase #6	$142.81	6.782%	$152.4954	$152.50	$152.50	$152.50
Purchase #7	$146.85	10.619%	$162.444	$162.44	$162.45	$162.40
7 purchase totals =	$1,030.27		$1,111.4154	$1,111.42	$1,111.40	$1,111.50