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	$57.25	13.494%	$64.9753	$64.98	$65.00	$65.00
Purchase #2	$179.83	3.216%	$185.6133	$185.61	$185.60	$185.60
Purchase #3	$240.56	6.383%	$255.9149	$255.91	$255.90	$255.90
Purchase #4	$215.48	3.469%	$222.955	$222.96	$222.95	$223.00
Purchase #5	$142.25	13.349%	$161.239	$161.24	$161.25	$161.20
Purchase #6	$104.41	3.525%	$108.0905	$108.09	$108.10	$108.10
Purchase #7	$21.89	12.252%	$24.572	$24.57	$24.55	$24.60
7 purchase totals =	$961.67		$1,023.3600	$1,023.36	$1,023.35	$1,023.40