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	$151.38	7.648%	$162.9575	$162.96	$162.95	$163.00
Purchase #2	$55.31	3.565%	$57.2818	$57.28	$57.30	$57.30
Purchase #3	$243.78	4.506%	$254.7647	$254.76	$254.75	$254.80
Purchase #4	$128.44	12.500%	$144.495	$144.50	$144.50	$144.50
Purchase #5	$105.79	6.183%	$112.331	$112.33	$112.35	$112.30
Purchase #6	$219.55	5.406%	$231.4189	$231.42	$231.40	$231.40
Purchase #7	$160.90	11.156%	$178.85	$178.85	$178.85	$178.90
7 purchase totals =	$1,065.15		$1,142.0989	$1,142.10	$1,142.10	$1,142.20