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	$184.51	11.607%	$205.9261	$205.93	$205.95	$205.90
Purchase #2	$139.71	7.711%	$150.483	$150.48	$150.50	$150.50
Purchase #3	$82.75	5.337%	$87.1664	$87.17	$87.15	$87.20
Purchase #4	$133.38	6.340%	$141.8363	$141.84	$141.85	$141.80
Purchase #5	$30.76	4.348%	$32.0974	$32.10	$32.10	$32.10
Purchase #6	$237.51	12.636%	$267.5218	$267.52	$267.50	$267.50
Purchase #7	$160.41	4.419%	$167.4985	$167.50	$167.50	$167.50
7 purchase totals =	$969.03		$1,052.5295	$1,052.54	$1,052.55	$1,052.50