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	$186.36	5.445%	$196.5073	$196.51	$196.50	$196.50
Purchase #2	$11.69	8.193%	$12.6478	$12.65	$12.65	$12.60
Purchase #3	$62.29	4.211%	$64.913	$64.91	$64.90	$64.90
Purchase #4	$151.50	11.476%	$168.8861	$168.89	$168.90	$168.90
Purchase #5	$29.78	11.753%	$33.28	$33.28	$33.30	$33.30
Purchase #6	$202.99	12.345%	$228.0491	$228.05	$228.05	$228.00
Purchase #7	$27.78	13.358%	$31.4909	$31.49	$31.50	$31.50
7 purchase totals =	$672.39		$735.7742	$735.78	$735.80	$735.70