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	$162.66	13.219%	$184.162	$184.16	$184.15	$184.20
Purchase #2	$216.65	3.188%	$223.5568	$223.56	$223.55	$223.60
Purchase #3	$6.73	3.699%	$6.9789	$6.98	$7.00	$7.00
Purchase #4	$182.50	5.454%	$192.4536	$192.45	$192.45	$192.50
Purchase #5	$241.85	12.517%	$272.1224	$272.12	$272.10	$272.10
Purchase #6	$79.71	3.586%	$82.5684	$82.57	$82.55	$82.60
Purchase #7	$177.68	7.523%	$191.0469	$191.05	$191.05	$191.00
7 purchase totals =	$1,067.78		$1,152.8890	$1,152.89	$1,152.85	$1,153.00