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	$222.94	9.132%	$243.2989	$243.30	$243.30	$243.30
Purchase #2	$46.74	3.534%	$48.3918	$48.39	$48.40	$48.40
Purchase #3	$52.39	9.693%	$57.4682	$57.47	$57.45	$57.50
Purchase #4	$200.85	10.418%	$221.7746	$221.77	$221.75	$221.80
Purchase #5	$33.72	9.790%	$37.0212	$37.02	$37.00	$37.00
Purchase #6	$209.94	4.834%	$220.0885	$220.09	$220.10	$220.10
Purchase #7	$193.90	11.855%	$216.8868	$216.89	$216.90	$216.90
7 purchase totals =	$960.48		$1,044.9300	$1,044.93	$1,044.90	$1,045.00