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	$218.96	10.342%	$241.6048	$241.60	$241.60	$241.60
Purchase #2	$69.55	13.146%	$78.693	$78.69	$78.70	$78.70
Purchase #3	$82.90	4.832%	$86.9057	$86.91	$86.90	$86.90
Purchase #4	$167.65	5.765%	$177.315	$177.32	$177.30	$177.30
Purchase #5	$81.69	11.489%	$91.0754	$91.08	$91.10	$91.10
Purchase #6	$43.45	3.344%	$44.903	$44.90	$44.90	$44.90
Purchase #7	$36.29	10.279%	$40.0202	$40.02	$40.00	$40.00
7 purchase totals =	$700.49		$760.5171	$760.52	$760.50	$760.50