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	$179.77	9.739%	$197.2778	$197.28	$197.30	$197.30
Purchase #2	$37.52	11.468%	$41.8228	$41.82	$41.80	$41.80
Purchase #3	$95.37	7.441%	$102.4665	$102.47	$102.45	$102.50
Purchase #4	$79.41	10.214%	$87.5209	$87.52	$87.50	$87.50
Purchase #5	$243.49	12.309%	$273.4612	$273.46	$273.45	$273.50
Purchase #6	$52.59	5.559%	$55.5135	$55.51	$55.50	$55.50
Purchase #7	$227.60	12.695%	$256.4938	$256.49	$256.50	$256.50
7 purchase totals =	$915.75		$1,014.5565	$1,014.55	$1,014.50	$1,014.60