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	$58.25	12.365%	$65.4526	$65.45	$65.45	$65.50
Purchase #2	$148.74	4.391%	$155.2712	$155.27	$155.25	$155.30
Purchase #3	$86.46	11.493%	$96.3968	$96.40	$96.40	$96.40
Purchase #4	$239.31	7.561%	$257.4042	$257.40	$257.40	$257.40
Purchase #5	$29.57	13.290%	$33.4999	$33.50	$33.50	$33.50
Purchase #6	$160.77	4.697%	$168.3214	$168.32	$168.30	$168.30
Purchase #7	$223.80	11.804%	$250.2174	$250.22	$250.20	$250.20
7 purchase totals =	$946.90		$1,026.5635	$1,026.56	$1,026.50	$1,026.60