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	$158.36	4.474%	$165.445	$165.45	$165.45	$165.40
Purchase #2	$181.92	4.759%	$190.5776	$190.58	$190.60	$190.60
Purchase #3	$96.81	12.634%	$109.041	$109.04	$109.05	$109.00
Purchase #4	$205.75	9.594%	$225.4897	$225.49	$225.50	$225.50
Purchase #5	$191.94	3.588%	$198.8268	$198.83	$198.85	$198.80
Purchase #6	$94.53	11.529%	$105.4284	$105.43	$105.45	$105.40
Purchase #7	$26.28	6.127%	$27.8902	$27.89	$27.90	$27.90
7 purchase totals =	$955.59		$1,022.6987	$1,022.71	$1,022.80	$1,022.60