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	$98.28	6.293%	$104.4648	$104.46	$104.45	$104.50
Purchase #2	$190.43	3.414%	$196.9313	$196.93	$196.95	$196.90
Purchase #3	$162.38	13.732%	$184.678	$184.68	$184.70	$184.70
Purchase #4	$9.48	12.616%	$10.676	$10.68	$10.70	$10.70
Purchase #5	$156.33	7.288%	$167.7233	$167.72	$167.70	$167.70
Purchase #6	$63.25	5.250%	$66.5706	$66.57	$66.55	$66.60
Purchase #7	$241.62	13.274%	$273.6926	$273.69	$273.70	$273.70
7 purchase totals =	$921.77		$1,004.7366	$1,004.73	$1,004.75	$1,004.80