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	$168.67	5.273%	$177.564	$177.56	$177.55	$177.60
Purchase #2	$29.57	6.629%	$31.5302	$31.53	$31.55	$31.50
Purchase #3	$232.63	13.607%	$264.284	$264.28	$264.30	$264.30
Purchase #4	$178.74	11.273%	$198.8894	$198.89	$198.90	$198.90
Purchase #5	$193.57	6.852%	$206.8334	$206.83	$206.85	$206.80
Purchase #6	$32.35	12.808%	$36.4934	$36.49	$36.50	$36.50
Purchase #7	$96.53	3.440%	$99.8506	$99.85	$99.85	$99.90
7 purchase totals =	$932.06		$1,015.4450	$1,015.43	$1,015.50	$1,015.50