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	$174.26	12.778%	$196.5269	$196.53	$196.55	$196.50
Purchase #2	$69.90	7.772%	$75.3326	$75.33	$75.35	$75.30
Purchase #3	$86.40	3.301%	$89.2521	$89.25	$89.25	$89.30
Purchase #4	$152.28	5.498%	$160.6524	$160.65	$160.65	$160.70
Purchase #5	$116.82	3.180%	$120.5349	$120.53	$120.55	$120.50
Purchase #6	$53.40	11.358%	$59.4652	$59.47	$59.45	$59.50
Purchase #7	$101.35	11.458%	$112.9627	$112.96	$112.95	$113.00
7 purchase totals =	$754.41		$814.7268	$814.72	$814.75	$814.80