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	$238.44	3.140%	$245.927	$245.93	$245.95	$245.90
Purchase #2	$113.78	13.123%	$128.7113	$128.71	$128.70	$128.70
Purchase #3	$162.53	13.769%	$184.9088	$184.91	$184.90	$184.90
Purchase #4	$33.95	8.321%	$36.775	$36.78	$36.80	$36.80
Purchase #5	$140.46	6.850%	$150.0815	$150.08	$150.10	$150.10
Purchase #6	$91.39	9.512%	$100.083	$100.08	$100.10	$100.10
Purchase #7	$200.77	3.863%	$208.5257	$208.53	$208.55	$208.50
7 purchase totals =	$981.32		$1,055.0123	$1,055.02	$1,055.10	$1,055.00