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	$199.34	3.376%	$206.0697	$206.07	$206.05	$206.10
Purchase #2	$107.90	11.152%	$119.933	$119.93	$119.95	$119.90
Purchase #3	$247.66	5.327%	$260.8528	$260.85	$260.85	$260.90
Purchase #4	$82.87	7.736%	$89.2808	$89.28	$89.30	$89.30
Purchase #5	$91.59	7.617%	$98.5664	$98.57	$98.55	$98.60
Purchase #6	$196.59	3.728%	$203.9189	$203.92	$203.90	$203.90
Purchase #7	$123.69	11.533%	$137.9552	$137.96	$137.95	$138.00
7 purchase totals =	$1,049.64		$1,116.5768	$1,116.58	$1,116.55	$1,116.70