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	$219.48	12.121%	$246.0832	$246.08	$246.10	$246.10
Purchase #2	$14.38	10.526%	$15.8936	$15.89	$15.90	$15.90
Purchase #3	$59.27	4.468%	$61.9182	$61.92	$61.90	$61.90
Purchase #4	$227.49	6.148%	$241.4761	$241.48	$241.50	$241.50
Purchase #5	$75.32	5.193%	$79.2314	$79.23	$79.25	$79.20
Purchase #6	$171.99	13.681%	$195.52	$195.52	$195.50	$195.50
Purchase #7	$236.61	5.229%	$248.9823	$248.98	$249.00	$249.00
7 purchase totals =	$1,004.54		$1,089.1048	$1,089.10	$1,089.15	$1,089.10