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	$162.42	7.794%	$175.079	$175.08	$175.10	$175.10
Purchase #2	$176.52	4.843%	$185.0689	$185.07	$185.05	$185.10
Purchase #3	$241.47	7.818%	$260.3481	$260.35	$260.35	$260.30
Purchase #4	$127.82	10.193%	$140.8487	$140.85	$140.85	$140.80
Purchase #5	$44.81	11.823%	$50.1079	$50.11	$50.10	$50.10
Purchase #6	$34.67	8.123%	$37.4862	$37.49	$37.50	$37.50
Purchase #7	$143.94	8.264%	$155.8352	$155.84	$155.85	$155.80
7 purchase totals =	$931.65		$1,004.7740	$1,004.79	$1,004.80	$1,004.70