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	$196.74	10.527%	$217.4508	$217.45	$217.45	$217.50
Purchase #2	$83.34	8.554%	$90.4689	$90.47	$90.45	$90.50
Purchase #3	$224.27	9.579%	$245.7528	$245.75	$245.75	$245.80
Purchase #4	$151.36	9.190%	$165.27	$165.27	$165.25	$165.30
Purchase #5	$20.29	3.277%	$20.9549	$20.95	$20.95	$21.00
Purchase #6	$114.47	13.866%	$130.3424	$130.34	$130.35	$130.30
Purchase #7	$181.74	4.577%	$190.0582	$190.06	$190.05	$190.10
7 purchase totals =	$972.21		$1,060.2980	$1,060.29	$1,060.25	$1,060.50