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	$213.89	4.781%	$224.1161	$224.12	$224.10	$224.10
Purchase #2	$155.34	4.279%	$161.987	$161.99	$162.00	$162.00
Purchase #3	$187.90	9.329%	$205.4292	$205.43	$205.45	$205.40
Purchase #4	$150.94	9.723%	$165.6159	$165.62	$165.60	$165.60
Purchase #5	$61.44	6.794%	$65.6142	$65.61	$65.60	$65.60
Purchase #6	$154.88	3.665%	$160.5564	$160.56	$160.55	$160.60
Purchase #7	$100.68	10.304%	$111.0541	$111.05	$111.05	$111.10
7 purchase totals =	$1,025.07		$1,094.3729	$1,094.38	$1,094.35	$1,094.40