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	$119.54	9.664%	$131.0923	$131.09	$131.10	$131.10
Purchase #2	$47.37	4.525%	$49.5135	$49.51	$49.50	$49.50
Purchase #3	$105.34	13.108%	$119.148	$119.15	$119.15	$119.10
Purchase #4	$204.32	12.239%	$229.3267	$229.33	$229.35	$229.30
Purchase #5	$195.65	10.604%	$216.3967	$216.40	$216.40	$216.40
Purchase #6	$96.36	9.551%	$105.5633	$105.56	$105.55	$105.60
Purchase #7	$163.76	6.811%	$174.9137	$174.91	$174.90	$174.90
7 purchase totals =	$932.34		$1,025.9542	$1,025.95	$1,025.95	$1,025.90