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	$142.66	3.638%	$147.85	$147.85	$147.85	$147.90
Purchase #2	$148.99	13.174%	$168.6179	$168.62	$168.60	$168.60
Purchase #3	$239.29	6.371%	$254.5352	$254.54	$254.55	$254.50
Purchase #4	$34.93	6.506%	$37.2025	$37.20	$37.20	$37.20
Purchase #5	$85.65	5.153%	$90.0635	$90.06	$90.05	$90.10
Purchase #6	$158.33	10.678%	$175.2365	$175.24	$175.25	$175.20
Purchase #7	$134.56	3.673%	$139.5024	$139.50	$139.50	$139.50
7 purchase totals =	$944.41		$1,013.0080	$1,013.01	$1,013.00	$1,013.00