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	$114.27	7.158%	$122.4494	$122.45	$122.45	$122.40
Purchase #2	$196.78	8.698%	$213.8959	$213.90	$213.90	$213.90
Purchase #3	$232.30	10.328%	$256.2919	$256.29	$256.30	$256.30
Purchase #4	$217.79	7.229%	$233.534	$233.53	$233.55	$233.50
Purchase #5	$148.76	3.760%	$154.3534	$154.35	$154.35	$154.40
Purchase #6	$48.56	11.654%	$54.2192	$54.22	$54.20	$54.20
Purchase #7	$12.69	5.816%	$13.4281	$13.43	$13.45	$13.40
7 purchase totals =	$971.15		$1,048.1719	$1,048.17	$1,048.20	$1,048.10