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	$191.46	4.457%	$199.9934	$199.99	$200.00	$200.00
Purchase #2	$11.48	8.556%	$12.4622	$12.46	$12.45	$12.50
Purchase #3	$36.86	11.478%	$41.0908	$41.09	$41.10	$41.10
Purchase #4	$98.46	11.654%	$109.9345	$109.93	$109.95	$109.90
Purchase #5	$167.97	11.844%	$187.8644	$187.86	$187.85	$187.90
Purchase #6	$168.95	13.590%	$191.9103	$191.91	$191.90	$191.90
Purchase #7	$100.49	7.350%	$107.876	$107.88	$107.90	$107.90
7 purchase totals =	$775.67		$851.1316	$851.12	$851.15	$851.20