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	$62.92	7.178%	$67.4364	$67.44	$67.45	$67.40
Purchase #2	$236.41	3.469%	$244.6111	$244.61	$244.60	$244.60
Purchase #3	$19.29	8.301%	$20.8913	$20.89	$20.90	$20.90
Purchase #4	$163.36	13.823%	$185.9413	$185.94	$185.95	$185.90
Purchase #5	$125.25	13.774%	$142.5019	$142.50	$142.50	$142.50
Purchase #6	$86.86	13.390%	$98.4906	$98.49	$98.50	$98.50
Purchase #7	$236.98	12.183%	$265.8513	$265.85	$265.85	$265.90
7 purchase totals =	$931.07		$1,025.7239	$1,025.72	$1,025.75	$1,025.70