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	$186.53	6.430%	$198.5239	$198.52	$198.50	$198.50
Purchase #2	$53.65	6.584%	$57.1823	$57.18	$57.20	$57.20
Purchase #3	$169.83	13.264%	$192.3563	$192.36	$192.35	$192.40
Purchase #4	$154.71	6.223%	$164.3376	$164.34	$164.35	$164.30
Purchase #5	$123.43	4.346%	$128.7943	$128.79	$128.80	$128.80
Purchase #6	$182.67	3.422%	$188.921	$188.92	$188.90	$188.90
Purchase #7	$87.67	8.851%	$95.4297	$95.43	$95.45	$95.40
7 purchase totals =	$958.49		$1,025.5451	$1,025.54	$1,025.55	$1,025.50