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	$199.30	4.844%	$208.9541	$208.95	$208.95	$209.00
Purchase #2	$168.94	4.506%	$176.5524	$176.55	$176.55	$176.60
Purchase #3	$243.41	11.301%	$270.9178	$270.92	$270.90	$270.90
Purchase #4	$247.25	11.411%	$275.4637	$275.46	$275.45	$275.50
Purchase #5	$156.75	3.507%	$162.2472	$162.25	$162.25	$162.20
Purchase #6	$99.46	13.621%	$113.0074	$113.01	$113.00	$113.00
Purchase #7	$150.28	3.316%	$155.2633	$155.26	$155.25	$155.30
7 purchase totals =	$1,265.39		$1,362.4059	$1,362.40	$1,362.35	$1,362.50