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	$181.81	3.481%	$188.1388	$188.14	$188.15	$188.10
Purchase #2	$206.51	13.707%	$234.8163	$234.82	$234.80	$234.80
Purchase #3	$245.46	7.209%	$263.1552	$263.16	$263.15	$263.20
Purchase #4	$176.84	7.219%	$189.6061	$189.61	$189.60	$189.60
Purchase #5	$89.94	10.525%	$99.4062	$99.41	$99.40	$99.40
Purchase #6	$146.36	8.304%	$158.5137	$158.51	$158.50	$158.50
Purchase #7	$25.93	5.667%	$27.3995	$27.40	$27.40	$27.40
7 purchase totals =	$1,072.85		$1,161.0358	$1,161.05	$1,161.00	$1,161.00