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	$126.88	3.434%	$131.2371	$131.24	$131.25	$131.20
Purchase #2	$163.36	11.164%	$181.5975	$181.60	$181.60	$181.60
Purchase #3	$167.36	7.522%	$179.9488	$179.95	$179.95	$179.90
Purchase #4	$182.89	12.145%	$205.102	$205.10	$205.10	$205.10
Purchase #5	$216.29	11.527%	$241.2217	$241.22	$241.20	$241.20
Purchase #6	$30.31	12.665%	$34.1488	$34.15	$34.15	$34.10
Purchase #7	$74.33	5.360%	$78.3141	$78.31	$78.30	$78.30
7 purchase totals =	$961.42		$1,051.5700	$1,051.57	$1,051.55	$1,051.40