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	$112.80	10.491%	$124.6338	$124.63	$124.65	$124.60
Purchase #2	$244.67	7.474%	$262.9566	$262.96	$262.95	$263.00
Purchase #3	$166.84	11.182%	$185.496	$185.50	$185.50	$185.50
Purchase #4	$186.52	7.516%	$200.5388	$200.54	$200.55	$200.50
Purchase #5	$64.75	11.465%	$72.1736	$72.17	$72.15	$72.20
Purchase #6	$78.72	9.791%	$86.4275	$86.43	$86.45	$86.40
Purchase #7	$168.74	3.163%	$174.0772	$174.08	$174.10	$174.10
7 purchase totals =	$1,023.04		$1,106.3035	$1,106.31	$1,106.35	$1,106.30