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	$53.74	11.175%	$59.7454	$59.75	$59.75	$59.70
Purchase #2	$157.82	7.552%	$169.7386	$169.74	$169.75	$169.70
Purchase #3	$109.77	7.380%	$117.871	$117.87	$117.85	$117.90
Purchase #4	$82.98	10.690%	$91.8506	$91.85	$91.85	$91.90
Purchase #5	$242.27	10.156%	$266.8749	$266.87	$266.85	$266.90
Purchase #6	$80.34	11.719%	$89.755	$89.76	$89.75	$89.80
Purchase #7	$199.33	9.870%	$219.0039	$219.00	$219.00	$219.00
7 purchase totals =	$926.25		$1,014.8394	$1,014.84	$1,014.80	$1,014.90