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	$145.33	7.215%	$155.8156	$155.82	$155.80	$155.80
Purchase #2	$57.57	7.317%	$61.7824	$61.78	$61.80	$61.80
Purchase #3	$131.91	3.776%	$136.8909	$136.89	$136.90	$136.90
Purchase #4	$239.52	10.429%	$264.4995	$264.50	$264.50	$264.50
Purchase #5	$238.52	10.727%	$264.106	$264.11	$264.10	$264.10
Purchase #6	$138.72	3.698%	$143.8499	$143.85	$143.85	$143.80
Purchase #7	$131.66	4.264%	$137.274	$137.27	$137.25	$137.30
7 purchase totals =	$1,083.23		$1,164.2183	$1,164.22	$1,164.20	$1,164.20