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	$194.72	11.309%	$216.7409	$216.74	$216.75	$216.70
Purchase #2	$101.59	4.322%	$105.9807	$105.98	$106.00	$106.00
Purchase #3	$90.97	10.627%	$100.6374	$100.64	$100.65	$100.60
Purchase #4	$74.77	4.136%	$77.8625	$77.86	$77.85	$77.90
Purchase #5	$250.62	6.539%	$267.008	$267.01	$267.00	$267.00
Purchase #6	$212.48	12.167%	$238.3324	$238.33	$238.35	$238.30
Purchase #7	$239.97	6.435%	$255.4121	$255.41	$255.40	$255.40
7 purchase totals =	$1,165.12		$1,261.9740	$1,261.97	$1,262.00	$1,261.90