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	$63.31	6.830%	$67.6341	$67.63	$67.65	$67.60
Purchase #2	$146.49	4.299%	$152.7876	$152.79	$152.80	$152.80
Purchase #3	$90.30	10.133%	$99.4501	$99.45	$99.45	$99.50
Purchase #4	$156.75	10.582%	$173.3373	$173.34	$173.35	$173.30
Purchase #5	$244.90	4.701%	$256.4127	$256.41	$256.40	$256.40
Purchase #6	$224.72	7.307%	$241.1403	$241.14	$241.15	$241.10
Purchase #7	$71.79	4.382%	$74.9358	$74.94	$74.95	$74.90
7 purchase totals =	$998.26		$1,065.6979	$1,065.70	$1,065.75	$1,065.60