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	$200.70	3.708%	$208.142	$208.14	$208.15	$208.10
Purchase #2	$8.49	3.515%	$8.7884	$8.79	$8.80	$8.80
Purchase #3	$183.81	8.234%	$198.9449	$198.94	$198.95	$198.90
Purchase #4	$152.33	6.384%	$162.0547	$162.05	$162.05	$162.10
Purchase #5	$229.36	5.763%	$242.578	$242.58	$242.60	$242.60
Purchase #6	$80.61	3.807%	$83.6788	$83.68	$83.70	$83.70
Purchase #7	$176.77	11.223%	$196.6089	$196.61	$196.60	$196.60
7 purchase totals =	$1,032.07		$1,100.7957	$1,100.79	$1,100.85	$1,100.80