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	$119.37	10.686%	$132.1259	$132.13	$132.15	$132.10
Purchase #2	$134.79	5.364%	$142.0201	$142.02	$142.00	$142.00
Purchase #3	$89.62	13.132%	$101.3889	$101.39	$101.40	$101.40
Purchase #4	$190.74	6.817%	$203.7427	$203.74	$203.75	$203.70
Purchase #5	$127.57	11.622%	$142.3962	$142.40	$142.40	$142.40
Purchase #6	$148.44	5.143%	$156.0743	$156.07	$156.05	$156.10
Purchase #7	$197.88	12.632%	$222.8762	$222.88	$222.90	$222.90
7 purchase totals =	$1,008.41		$1,100.6243	$1,100.63	$1,100.65	$1,100.60