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	$78.62	9.294%	$85.9269	$85.93	$85.95	$85.90
Purchase #2	$64.57	10.184%	$71.1458	$71.15	$71.15	$71.10
Purchase #3	$36.32	9.498%	$39.7697	$39.77	$39.75	$39.80
Purchase #4	$15.35	10.754%	$17.0007	$17.00	$17.00	$17.00
Purchase #5	$231.63	13.300%	$262.4368	$262.44	$262.45	$262.40
Purchase #6	$234.62	11.357%	$261.2658	$261.27	$261.25	$261.30
Purchase #7	$231.93	13.658%	$263.607	$263.61	$263.60	$263.60
7 purchase totals =	$893.04		$1,001.1527	$1,001.17	$1,001.15	$1,001.10