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	$82.61	4.376%	$86.225	$86.23	$86.25	$86.20
Purchase #2	$164.68	5.598%	$173.8988	$173.90	$173.90	$173.90
Purchase #3	$50.25	7.837%	$54.1881	$54.19	$54.20	$54.20
Purchase #4	$194.49	12.561%	$218.9199	$218.92	$218.90	$218.90
Purchase #5	$208.95	6.258%	$222.0261	$222.03	$222.05	$222.00
Purchase #6	$240.29	5.432%	$253.3426	$253.34	$253.35	$253.30
Purchase #7	$152.42	12.819%	$171.9587	$171.96	$171.95	$172.00
7 purchase totals =	$1,093.69		$1,180.5592	$1,180.57	$1,180.60	$1,180.50