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	$153.31	12.620%	$172.6577	$172.66	$172.65	$172.70
Purchase #2	$103.43	12.480%	$116.3381	$116.34	$116.35	$116.30
Purchase #3	$54.94	7.747%	$59.1962	$59.20	$59.20	$59.20
Purchase #4	$236.88	7.229%	$254.0041	$254.00	$254.00	$254.00
Purchase #5	$56.83	4.300%	$59.2737	$59.27	$59.25	$59.30
Purchase #6	$128.66	6.481%	$136.9985	$137.00	$137.00	$137.00
Purchase #7	$214.83	5.743%	$227.1677	$227.17	$227.15	$227.20
7 purchase totals =	$948.88		$1,025.6360	$1,025.64	$1,025.60	$1,025.70