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	$58.25	12.840%	$65.7293	$65.73	$65.75	$65.70
Purchase #2	$112.40	13.213%	$127.2514	$127.25	$127.25	$127.30
Purchase #3	$29.81	6.526%	$31.7554	$31.76	$31.75	$31.80
Purchase #4	$212.80	10.139%	$234.3758	$234.38	$234.40	$234.40
Purchase #5	$221.75	3.510%	$229.5334	$229.53	$229.55	$229.50
Purchase #6	$5.90	7.614%	$6.3492	$6.35	$6.35	$6.30
Purchase #7	$97.73	11.764%	$109.227	$109.23	$109.25	$109.20
7 purchase totals =	$738.64		$804.2215	$804.23	$804.30	$804.20