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	$195.84	9.189%	$213.8357	$213.84	$213.85	$213.80
Purchase #2	$91.61	4.239%	$95.4933	$95.49	$95.50	$95.50
Purchase #3	$140.95	4.581%	$147.4069	$147.41	$147.40	$147.40
Purchase #4	$248.85	6.851%	$265.8987	$265.90	$265.90	$265.90
Purchase #5	$115.50	13.715%	$131.3408	$131.34	$131.35	$131.30
Purchase #6	$92.40	7.250%	$99.099	$99.10	$99.10	$99.10
Purchase #7	$169.82	13.465%	$192.6863	$192.69	$192.70	$192.70
7 purchase totals =	$1,054.97		$1,145.7607	$1,145.77	$1,145.80	$1,145.70