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	$192.40	11.150%	$213.8526	$213.85	$213.85	$213.90
Purchase #2	$180.48	4.369%	$188.3652	$188.37	$188.35	$188.40
Purchase #3	$226.26	10.538%	$250.1033	$250.10	$250.10	$250.10
Purchase #4	$148.88	6.252%	$158.188	$158.19	$158.20	$158.20
Purchase #5	$151.27	11.657%	$168.9035	$168.90	$168.90	$168.90
Purchase #6	$44.29	13.606%	$50.3161	$50.32	$50.30	$50.30
Purchase #7	$115.94	6.627%	$123.6233	$123.62	$123.60	$123.60
7 purchase totals =	$1,059.52		$1,153.3520	$1,153.35	$1,153.30	$1,153.40