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	$158.80	5.620%	$167.7246	$167.72	$167.70	$167.70
Purchase #2	$215.28	5.505%	$227.1312	$227.13	$227.15	$227.10
Purchase #3	$208.83	11.324%	$232.4779	$232.48	$232.50	$232.50
Purchase #4	$12.40	12.484%	$13.948	$13.95	$13.95	$13.90
Purchase #5	$52.84	3.158%	$54.5087	$54.51	$54.50	$54.50
Purchase #6	$220.60	12.522%	$248.2235	$248.22	$248.20	$248.20
Purchase #7	$61.82	5.404%	$65.1608	$65.16	$65.15	$65.20
7 purchase totals =	$930.57		$1,009.1747	$1,009.17	$1,009.15	$1,009.10