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	$113.40	4.343%	$118.325	$118.33	$118.35	$118.30
Purchase #2	$207.38	8.499%	$225.0052	$225.01	$225.00	$225.00
Purchase #3	$15.95	13.666%	$18.1297	$18.13	$18.15	$18.10
Purchase #4	$233.58	9.796%	$256.4615	$256.46	$256.45	$256.50
Purchase #5	$244.35	12.772%	$275.5584	$275.56	$275.55	$275.60
Purchase #6	$154.58	13.780%	$175.8811	$175.88	$175.90	$175.90
Purchase #7	$56.35	6.396%	$59.9541	$59.95	$59.95	$60.00
7 purchase totals =	$1,025.59		$1,129.3150	$1,129.32	$1,129.35	$1,129.40