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	$204.63	3.169%	$211.1147	$211.11	$211.10	$211.10
Purchase #2	$85.44	11.778%	$95.5031	$95.50	$95.50	$95.50
Purchase #3	$164.28	13.574%	$186.5794	$186.58	$186.60	$186.60
Purchase #4	$106.49	7.676%	$114.6642	$114.66	$114.65	$114.70
Purchase #5	$133.94	6.431%	$142.5537	$142.55	$142.55	$142.60
Purchase #6	$213.53	4.146%	$222.383	$222.38	$222.40	$222.40
Purchase #7	$159.62	6.270%	$169.6282	$169.63	$169.65	$169.60
7 purchase totals =	$1,067.93		$1,142.4263	$1,142.41	$1,142.45	$1,142.50