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	$103.84	3.561%	$107.5377	$107.54	$107.55	$107.50
Purchase #2	$9.62	12.805%	$10.8518	$10.85	$10.85	$10.90
Purchase #3	$173.72	10.109%	$191.2814	$191.28	$191.30	$191.30
Purchase #4	$233.78	9.638%	$256.3117	$256.31	$256.30	$256.30
Purchase #5	$225.93	6.311%	$240.1884	$240.19	$240.20	$240.20
Purchase #6	$58.56	4.732%	$61.3311	$61.33	$61.35	$61.30
Purchase #7	$163.67	6.864%	$174.9043	$174.90	$174.90	$174.90
7 purchase totals =	$969.12		$1,042.4064	$1,042.40	$1,042.45	$1,042.40