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	$175.77	12.750%	$198.1807	$198.18	$198.20	$198.20
Purchase #2	$64.38	12.622%	$72.506	$72.51	$72.50	$72.50
Purchase #3	$126.47	4.482%	$132.1384	$132.14	$132.15	$132.10
Purchase #4	$17.42	3.102%	$17.9604	$17.96	$17.95	$18.00
Purchase #5	$152.56	12.568%	$171.7337	$171.73	$171.75	$171.70
Purchase #6	$225.59	3.485%	$233.4518	$233.45	$233.45	$233.50
Purchase #7	$187.43	6.562%	$199.7292	$199.73	$199.75	$199.70
7 purchase totals =	$949.62		$1,025.7002	$1,025.70	$1,025.75	$1,025.70