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	$167.55	12.493%	$188.482	$188.48	$188.50	$188.50
Purchase #2	$37.96	7.652%	$40.8647	$40.86	$40.85	$40.90
Purchase #3	$103.83	13.826%	$118.1855	$118.19	$118.20	$118.20
Purchase #4	$195.77	3.812%	$203.2328	$203.23	$203.25	$203.20
Purchase #5	$167.30	9.179%	$182.6565	$182.66	$182.65	$182.70
Purchase #6	$237.80	7.751%	$256.2319	$256.23	$256.25	$256.20
Purchase #7	$112.81	10.320%	$124.452	$124.45	$124.45	$124.50
7 purchase totals =	$1,023.02		$1,114.1054	$1,114.10	$1,114.15	$1,114.20