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	$112.36	7.495%	$120.7814	$120.78	$120.80	$120.80
Purchase #2	$113.65	3.516%	$117.6459	$117.65	$117.65	$117.60
Purchase #3	$71.95	9.154%	$78.5363	$78.54	$78.55	$78.50
Purchase #4	$87.73	7.823%	$94.5931	$94.59	$94.60	$94.60
Purchase #5	$213.68	6.371%	$227.2936	$227.29	$227.30	$227.30
Purchase #6	$126.39	12.572%	$142.2798	$142.28	$142.30	$142.30
Purchase #7	$216.89	12.212%	$243.3766	$243.38	$243.40	$243.40
7 purchase totals =	$942.65		$1,024.5067	$1,024.51	$1,024.60	$1,024.50