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	$190.58	5.443%	$200.9533	$200.95	$200.95	$201.00
Purchase #2	$227.47	5.612%	$240.2356	$240.24	$240.25	$240.20
Purchase #3	$131.30	8.823%	$142.8846	$142.88	$142.90	$142.90
Purchase #4	$164.68	12.608%	$185.4429	$185.44	$185.45	$185.40
Purchase #5	$66.27	8.206%	$71.7081	$71.71	$71.70	$71.70
Purchase #6	$53.48	11.449%	$59.6029	$59.60	$59.60	$59.60
Purchase #7	$148.45	10.194%	$163.583	$163.58	$163.60	$163.60
7 purchase totals =	$982.23		$1,064.4104	$1,064.40	$1,064.45	$1,064.40