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	$168.56	13.484%	$191.2886	$191.29	$191.30	$191.30
Purchase #2	$12.98	5.766%	$13.7284	$13.73	$13.75	$13.70
Purchase #3	$143.61	11.580%	$160.24	$160.24	$160.25	$160.20
Purchase #4	$240.60	6.703%	$256.7274	$256.73	$256.75	$256.70
Purchase #5	$223.95	4.189%	$233.3313	$233.33	$233.35	$233.30
Purchase #6	$32.71	5.602%	$34.5424	$34.54	$34.55	$34.50
Purchase #7	$245.86	7.536%	$264.388	$264.39	$264.40	$264.40
7 purchase totals =	$1,068.27		$1,154.2461	$1,154.25	$1,154.35	$1,154.10