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	$189.39	3.442%	$195.9088	$195.91	$195.90	$195.90
Purchase #2	$85.82	7.794%	$92.5088	$92.51	$92.50	$92.50
Purchase #3	$54.85	11.242%	$61.0162	$61.02	$61.00	$61.00
Purchase #4	$24.60	11.308%	$27.3818	$27.38	$27.40	$27.40
Purchase #5	$230.53	4.601%	$241.1367	$241.14	$241.15	$241.10
Purchase #6	$92.69	13.670%	$105.3607	$105.36	$105.35	$105.40
Purchase #7	$248.46	11.677%	$277.4727	$277.47	$277.45	$277.50
7 purchase totals =	$926.34		$1,000.7857	$1,000.79	$1,000.75	$1,000.80