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	$185.85	12.406%	$208.9066	$208.91	$208.90	$208.90
Purchase #2	$94.60	6.834%	$101.065	$101.07	$101.05	$101.10
Purchase #3	$168.55	4.293%	$175.7859	$175.79	$175.80	$175.80
Purchase #4	$160.51	13.654%	$182.426	$182.43	$182.45	$182.40
Purchase #5	$96.75	3.126%	$99.7744	$99.77	$99.75	$99.80
Purchase #6	$157.89	4.521%	$165.0282	$165.03	$165.05	$165.00
Purchase #7	$203.69	3.565%	$210.9515	$210.95	$210.95	$211.00
7 purchase totals =	$1,067.84		$1,143.9376	$1,143.95	$1,143.95	$1,144.00