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	$216.71	13.214%	$245.3461	$245.35	$245.35	$245.30
Purchase #2	$65.46	8.669%	$71.1347	$71.13	$71.15	$71.10
Purchase #3	$128.56	11.102%	$142.8327	$142.83	$142.85	$142.80
Purchase #4	$111.94	6.846%	$119.6034	$119.60	$119.60	$119.60
Purchase #5	$6.73	6.255%	$7.151	$7.15	$7.15	$7.20
Purchase #6	$210.70	6.172%	$223.7044	$223.70	$223.70	$223.70
Purchase #7	$208.82	3.697%	$216.5401	$216.54	$216.55	$216.50
7 purchase totals =	$948.92		$1,026.3124	$1,026.30	$1,026.35	$1,026.20