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	$183.31	5.527%	$193.4415	$193.44	$193.45	$193.40
Purchase #2	$47.27	9.799%	$51.902	$51.90	$51.90	$51.90
Purchase #3	$57.52	3.792%	$59.7012	$59.70	$59.70	$59.70
Purchase #4	$112.97	3.370%	$116.7771	$116.78	$116.80	$116.80
Purchase #5	$157.49	4.740%	$164.955	$164.96	$164.95	$165.00
Purchase #6	$130.76	13.284%	$148.1302	$148.13	$148.15	$148.10
Purchase #7	$246.39	7.772%	$265.5394	$265.54	$265.55	$265.50
7 purchase totals =	$935.71		$1,000.4464	$1,000.45	$1,000.50	$1,000.40