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	$169.68	3.277%	$175.2404	$175.24	$175.25	$175.20
Purchase #2	$80.44	6.386%	$85.5769	$85.58	$85.60	$85.60
Purchase #3	$177.72	9.125%	$193.937	$193.94	$193.95	$193.90
Purchase #4	$167.52	4.147%	$174.4671	$174.47	$174.45	$174.50
Purchase #5	$75.32	9.502%	$82.4769	$82.48	$82.50	$82.50
Purchase #6	$135.92	10.545%	$150.2528	$150.25	$150.25	$150.30
Purchase #7	$162.55	8.590%	$176.513	$176.51	$176.50	$176.50
7 purchase totals =	$969.15		$1,038.4641	$1,038.47	$1,038.50	$1,038.50