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	$94.26	11.270%	$104.8831	$104.88	$104.90	$104.90
Purchase #2	$199.39	4.348%	$208.0595	$208.06	$208.05	$208.10
Purchase #3	$43.43	4.449%	$45.3622	$45.36	$45.35	$45.40
Purchase #4	$245.74	3.783%	$255.0363	$255.04	$255.05	$255.00
Purchase #5	$164.30	4.777%	$172.1486	$172.15	$172.15	$172.10
Purchase #6	$75.83	6.284%	$80.5952	$80.60	$80.60	$80.60
Purchase #7	$213.66	3.362%	$220.8432	$220.84	$220.85	$220.80
7 purchase totals =	$1,036.61		$1,086.9281	$1,086.93	$1,086.95	$1,086.90