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	$168.63	8.314%	$182.6499	$182.65	$182.65	$182.60
Purchase #2	$133.82	7.180%	$143.4283	$143.43	$143.45	$143.40
Purchase #3	$76.84	11.359%	$85.5683	$85.57	$85.55	$85.60
Purchase #4	$157.35	8.257%	$170.3424	$170.34	$170.35	$170.30
Purchase #5	$158.71	5.568%	$167.547	$167.55	$167.55	$167.50
Purchase #6	$205.30	13.576%	$233.1715	$233.17	$233.15	$233.20
Purchase #7	$171.63	4.614%	$179.549	$179.55	$179.55	$179.50
7 purchase totals =	$1,072.28		$1,162.2564	$1,162.26	$1,162.25	$1,162.10