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	$157.71	11.869%	$176.4286	$176.43	$176.45	$176.40
Purchase #2	$155.76	11.228%	$173.2487	$173.25	$173.25	$173.20
Purchase #3	$135.77	12.152%	$152.2688	$152.27	$152.25	$152.30
Purchase #4	$145.77	5.358%	$153.5804	$153.58	$153.60	$153.60
Purchase #5	$232.84	6.716%	$248.4775	$248.48	$248.50	$248.50
Purchase #6	$99.33	3.730%	$103.035	$103.04	$103.05	$103.00
Purchase #7	$69.34	4.185%	$72.2419	$72.24	$72.25	$72.20
7 purchase totals =	$996.52		$1,079.2809	$1,079.29	$1,079.35	$1,079.20