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	$94.43	7.116%	$101.1496	$101.15	$101.15	$101.10
Purchase #2	$214.43	9.556%	$234.9209	$234.92	$234.90	$234.90
Purchase #3	$11.63	10.808%	$12.887	$12.89	$12.90	$12.90
Purchase #4	$156.37	3.705%	$162.1635	$162.16	$162.15	$162.20
Purchase #5	$223.48	11.292%	$248.7154	$248.72	$248.70	$248.70
Purchase #6	$168.81	7.184%	$180.9373	$180.94	$180.95	$180.90
Purchase #7	$95.54	9.412%	$104.5322	$104.53	$104.55	$104.50
7 purchase totals =	$964.69		$1,045.3059	$1,045.31	$1,045.30	$1,045.20