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	$97.92	4.855%	$102.674	$102.67	$102.65	$102.70
Purchase #2	$50.68	5.644%	$53.5404	$53.54	$53.55	$53.50
Purchase #3	$132.29	9.524%	$144.8893	$144.89	$144.90	$144.90
Purchase #4	$230.94	4.247%	$240.748	$240.75	$240.75	$240.70
Purchase #5	$76.40	11.569%	$85.2387	$85.24	$85.25	$85.20
Purchase #6	$206.62	4.110%	$215.1121	$215.11	$215.10	$215.10
Purchase #7	$205.56	8.139%	$222.2905	$222.29	$222.30	$222.30
7 purchase totals =	$1,000.41		$1,064.4930	$1,064.49	$1,064.50	$1,064.40