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	$241.27	8.659%	$262.1616	$262.16	$262.15	$262.20
Purchase #2	$224.38	7.243%	$240.6318	$240.63	$240.65	$240.60
Purchase #3	$119.72	5.138%	$125.8712	$125.87	$125.85	$125.90
Purchase #4	$48.86	9.781%	$53.639	$53.64	$53.65	$53.60
Purchase #5	$61.45	10.505%	$67.9053	$67.91	$67.90	$67.90
Purchase #6	$240.39	9.637%	$263.5564	$263.56	$263.55	$263.60
Purchase #7	$177.82	5.209%	$187.0826	$187.08	$187.10	$187.10
7 purchase totals =	$1,113.89		$1,200.8479	$1,200.85	$1,200.85	$1,200.90