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	$181.64	8.375%	$196.8524	$196.85	$196.85	$196.90
Purchase #2	$71.61	11.120%	$79.573	$79.57	$79.55	$79.60
Purchase #3	$220.54	10.554%	$243.8158	$243.82	$243.80	$243.80
Purchase #4	$202.62	6.570%	$215.9321	$215.93	$215.95	$215.90
Purchase #5	$188.36	11.703%	$210.4038	$210.40	$210.40	$210.40
Purchase #6	$95.58	7.666%	$102.9072	$102.91	$102.90	$102.90
Purchase #7	$170.80	4.289%	$178.1256	$178.13	$178.15	$178.10
7 purchase totals =	$1,131.15		$1,227.6099	$1,227.61	$1,227.60	$1,227.60