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	$124.67	5.419%	$131.4259	$131.43	$131.45	$131.40
Purchase #2	$92.81	7.218%	$99.509	$99.51	$99.50	$99.50
Purchase #3	$48.25	4.159%	$50.2567	$50.26	$50.25	$50.30
Purchase #4	$194.63	12.195%	$218.3651	$218.37	$218.35	$218.40
Purchase #5	$234.57	3.114%	$241.8745	$241.87	$241.85	$241.90
Purchase #6	$171.63	12.784%	$193.5712	$193.57	$193.55	$193.60
Purchase #7	$186.44	13.440%	$211.4975	$211.50	$211.50	$211.50
7 purchase totals =	$1,053.00		$1,146.4999	$1,146.51	$1,146.45	$1,146.60