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	$195.49	3.203%	$201.7515	$201.75	$201.75	$201.80
Purchase #2	$59.36	9.519%	$65.0105	$65.01	$65.00	$65.00
Purchase #3	$10.52	13.210%	$11.9097	$11.91	$11.90	$11.90
Purchase #4	$124.83	12.704%	$140.6884	$140.69	$140.70	$140.70
Purchase #5	$55.70	6.318%	$59.2191	$59.22	$59.20	$59.20
Purchase #6	$18.38	10.863%	$20.3766	$20.38	$20.40	$20.40
Purchase #7	$25.45	12.338%	$28.59	$28.59	$28.60	$28.60
7 purchase totals =	$489.73		$527.5458	$527.55	$527.55	$527.60