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	$196.82	8.684%	$213.9118	$213.91	$213.90	$213.90
Purchase #2	$234.57	12.775%	$264.5363	$264.54	$264.55	$264.50
Purchase #3	$218.38	12.332%	$245.3106	$245.31	$245.30	$245.30
Purchase #4	$195.50	11.249%	$217.4918	$217.49	$217.50	$217.50
Purchase #5	$204.88	8.402%	$222.094	$222.09	$222.10	$222.10
Purchase #6	$174.27	6.210%	$185.0922	$185.09	$185.10	$185.10
Purchase #7	$105.51	13.831%	$120.1031	$120.10	$120.10	$120.10
7 purchase totals =	$1,329.93		$1,468.5398	$1,468.53	$1,468.55	$1,468.50