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	$225.86	9.320%	$246.9102	$246.91	$246.90	$246.90
Purchase #2	$184.33	4.130%	$191.9428	$191.94	$191.95	$191.90
Purchase #3	$54.68	9.508%	$59.879	$59.88	$59.90	$59.90
Purchase #4	$142.85	9.805%	$156.8564	$156.86	$156.85	$156.90
Purchase #5	$131.60	11.571%	$146.8274	$146.83	$146.85	$146.80
Purchase #6	$146.55	5.157%	$154.1076	$154.11	$154.10	$154.10
Purchase #7	$198.66	5.798%	$210.1783	$210.18	$210.20	$210.20
7 purchase totals =	$1,084.53		$1,166.7017	$1,166.71	$1,166.75	$1,166.70