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	$96.53	4.601%	$100.9713	$100.97	$100.95	$101.00
Purchase #2	$144.77	13.458%	$164.2531	$164.25	$164.25	$164.30
Purchase #3	$174.65	6.502%	$186.0057	$186.01	$186.00	$186.00
Purchase #4	$139.45	9.184%	$152.2571	$152.26	$152.25	$152.30
Purchase #5	$70.30	3.310%	$72.6269	$72.63	$72.65	$72.60
Purchase #6	$187.44	6.785%	$200.1578	$200.16	$200.15	$200.20
Purchase #7	$164.34	11.290%	$182.894	$182.89	$182.90	$182.90
7 purchase totals =	$977.48		$1,059.1659	$1,059.17	$1,059.15	$1,059.30