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	$200.94	3.539%	$208.0513	$208.05	$208.05	$208.10
Purchase #2	$113.56	5.425%	$119.7206	$119.72	$119.70	$119.70
Purchase #3	$86.60	6.683%	$92.3875	$92.39	$92.40	$92.40
Purchase #4	$50.32	6.155%	$53.4172	$53.42	$53.40	$53.40
Purchase #5	$181.78	4.119%	$189.2675	$189.27	$189.25	$189.30
Purchase #6	$51.34	10.138%	$56.5448	$56.54	$56.55	$56.50
Purchase #7	$250.78	4.703%	$262.5742	$262.57	$262.55	$262.60
7 purchase totals =	$935.32		$981.9631	$981.96	$981.90	$982.00