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	$111.71	7.625%	$120.2279	$120.23	$120.25	$120.20
Purchase #2	$119.88	13.484%	$136.0446	$136.04	$136.05	$136.00
Purchase #3	$177.50	12.615%	$199.8916	$199.89	$199.90	$199.90
Purchase #4	$203.26	3.637%	$210.6526	$210.65	$210.65	$210.70
Purchase #5	$210.93	13.104%	$238.5703	$238.57	$238.55	$238.60
Purchase #6	$61.62	12.193%	$69.1333	$69.13	$69.15	$69.10
Purchase #7	$201.32	10.476%	$222.4103	$222.41	$222.40	$222.40
7 purchase totals =	$1,086.22		$1,196.9306	$1,196.92	$1,196.95	$1,196.90