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	$172.81	13.610%	$196.3294	$196.33	$196.35	$196.30
Purchase #2	$166.25	12.328%	$186.7453	$186.75	$186.75	$186.70
Purchase #3	$236.57	11.118%	$262.8719	$262.87	$262.85	$262.90
Purchase #4	$158.66	13.854%	$180.6408	$180.64	$180.65	$180.60
Purchase #5	$58.27	12.763%	$65.707	$65.71	$65.70	$65.70
Purchase #6	$147.82	3.565%	$153.0898	$153.09	$153.10	$153.10
Purchase #7	$56.53	4.550%	$59.1021	$59.10	$59.10	$59.10
7 purchase totals =	$996.91		$1,104.4863	$1,104.49	$1,104.50	$1,104.40