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	$192.42	4.325%	$200.7422	$200.74	$200.75	$200.70
Purchase #2	$68.38	6.610%	$72.8999	$72.90	$72.90	$72.90
Purchase #3	$171.46	4.783%	$179.6609	$179.66	$179.65	$179.70
Purchase #4	$155.35	4.396%	$162.1792	$162.18	$162.20	$162.20
Purchase #5	$176.58	10.777%	$195.61	$195.61	$195.60	$195.60
Purchase #6	$82.78	9.420%	$90.5779	$90.58	$90.60	$90.60
Purchase #7	$221.92	12.231%	$249.063	$249.06	$249.05	$249.10
7 purchase totals =	$1,068.89		$1,150.7331	$1,150.73	$1,150.75	$1,150.80