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	$115.84	10.802%	$128.353	$128.35	$128.35	$128.40
Purchase #2	$234.36	12.475%	$263.5964	$263.60	$263.60	$263.60
Purchase #3	$143.40	8.205%	$155.166	$155.17	$155.15	$155.20
Purchase #4	$104.61	5.545%	$110.4106	$110.41	$110.40	$110.40
Purchase #5	$202.80	9.602%	$222.2729	$222.27	$222.25	$222.30
Purchase #6	$192.62	5.690%	$203.5801	$203.58	$203.60	$203.60
Purchase #7	$25.85	10.333%	$28.5211	$28.52	$28.50	$28.50
7 purchase totals =	$1,019.48		$1,111.9001	$1,111.90	$1,111.85	$1,112.00