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	$157.96	11.372%	$175.9232	$175.92	$175.90	$175.90
Purchase #2	$96.53	13.324%	$109.3917	$109.39	$109.40	$109.40
Purchase #3	$164.96	6.542%	$175.7517	$175.75	$175.75	$175.80
Purchase #4	$206.79	3.221%	$213.4507	$213.45	$213.45	$213.50
Purchase #5	$46.58	12.689%	$52.4905	$52.49	$52.50	$52.50
Purchase #6	$160.61	5.506%	$169.4532	$169.45	$169.45	$169.50
Purchase #7	$114.79	12.281%	$128.8874	$128.89	$128.90	$128.90
7 purchase totals =	$948.22		$1,025.3484	$1,025.34	$1,025.35	$1,025.50