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	$212.52	12.115%	$238.2668	$238.27	$238.25	$238.30
Purchase #2	$187.28	4.724%	$196.1271	$196.13	$196.15	$196.10
Purchase #3	$217.33	4.369%	$226.8251	$226.83	$226.85	$226.80
Purchase #4	$153.71	5.401%	$162.0119	$162.01	$162.00	$162.00
Purchase #5	$176.83	8.550%	$191.949	$191.95	$191.95	$191.90
Purchase #6	$217.26	10.701%	$240.509	$240.51	$240.50	$240.50
Purchase #7	$107.81	9.552%	$118.108	$118.11	$118.10	$118.10
7 purchase totals =	$1,272.74		$1,373.7969	$1,373.81	$1,373.80	$1,373.70