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	$54.61	5.693%	$57.7189	$57.72	$57.70	$57.70
Purchase #2	$207.61	12.693%	$233.9619	$233.96	$233.95	$234.00
Purchase #3	$217.43	7.768%	$234.32	$234.32	$234.30	$234.30
Purchase #4	$168.75	13.800%	$192.0375	$192.04	$192.05	$192.00
Purchase #5	$215.31	5.588%	$227.3415	$227.34	$227.35	$227.30
Purchase #6	$244.82	9.532%	$268.1562	$268.16	$268.15	$268.20
Purchase #7	$55.65	7.264%	$59.6924	$59.69	$59.70	$59.70
7 purchase totals =	$1,164.18		$1,273.2284	$1,273.23	$1,273.20	$1,273.20