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	$177.86	10.747%	$196.9746	$196.97	$196.95	$197.00
Purchase #2	$77.86	9.370%	$85.1555	$85.16	$85.15	$85.20
Purchase #3	$72.70	13.180%	$82.2819	$82.28	$82.30	$82.30
Purchase #4	$244.78	6.836%	$261.5132	$261.51	$261.50	$261.50
Purchase #5	$172.98	5.597%	$182.6617	$182.66	$182.65	$182.70
Purchase #6	$153.42	8.780%	$166.8903	$166.89	$166.90	$166.90
Purchase #7	$116.62	11.652%	$130.2086	$130.21	$130.20	$130.20
7 purchase totals =	$1,016.22		$1,105.6858	$1,105.68	$1,105.65	$1,105.80