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	$208.33	4.645%	$218.0069	$218.01	$218.00	$218.00
Purchase #2	$187.79	6.667%	$200.31	$200.31	$200.30	$200.30
Purchase #3	$154.81	4.343%	$161.5334	$161.53	$161.55	$161.50
Purchase #4	$117.66	4.853%	$123.37	$123.37	$123.35	$123.40
Purchase #5	$88.36	8.123%	$95.5375	$95.54	$95.55	$95.50
Purchase #6	$78.91	9.113%	$86.1011	$86.10	$86.10	$86.10
Purchase #7	$169.97	3.332%	$175.6334	$175.63	$175.65	$175.60
7 purchase totals =	$1,005.83		$1,060.4923	$1,060.49	$1,060.50	$1,060.40