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	$94.69	11.175%	$105.2716	$105.27	$105.25	$105.30
Purchase #2	$233.66	9.503%	$255.8647	$255.86	$255.85	$255.90
Purchase #3	$191.42	5.419%	$201.793	$201.79	$201.80	$201.80
Purchase #4	$175.52	9.160%	$191.5976	$191.60	$191.60	$191.60
Purchase #5	$156.96	3.381%	$162.2668	$162.27	$162.25	$162.30
Purchase #6	$70.55	7.570%	$75.8906	$75.89	$75.90	$75.90
Purchase #7	$101.62	9.782%	$111.5605	$111.56	$111.55	$111.60
7 purchase totals =	$1,024.42		$1,104.2448	$1,104.24	$1,104.20	$1,104.40