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	$166.42	9.142%	$181.6341	$181.63	$181.65	$181.60
Purchase #2	$31.30	9.631%	$34.3145	$34.31	$34.30	$34.30
Purchase #3	$209.48	3.824%	$217.4905	$217.49	$217.50	$217.50
Purchase #4	$213.96	5.577%	$225.8925	$225.89	$225.90	$225.90
Purchase #5	$151.71	7.356%	$162.8698	$162.87	$162.85	$162.90
Purchase #6	$204.53	9.585%	$224.1342	$224.13	$224.15	$224.10
Purchase #7	$147.29	3.364%	$152.2448	$152.24	$152.25	$152.20
7 purchase totals =	$1,124.69		$1,198.5804	$1,198.56	$1,198.60	$1,198.50