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	$221.50	3.139%	$228.4529	$228.45	$228.45	$228.50
Purchase #2	$76.70	5.558%	$80.963	$80.96	$80.95	$81.00
Purchase #3	$80.63	6.318%	$85.7242	$85.72	$85.70	$85.70
Purchase #4	$129.39	9.285%	$141.4039	$141.40	$141.40	$141.40
Purchase #5	$224.46	10.669%	$248.4076	$248.41	$248.40	$248.40
Purchase #6	$189.52	5.726%	$200.3719	$200.37	$200.35	$200.40
Purchase #7	$24.52	3.708%	$25.4292	$25.43	$25.45	$25.40
7 purchase totals =	$946.72		$1,010.7527	$1,010.74	$1,010.70	$1,010.80