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	$148.98	3.331%	$153.9425	$153.94	$153.95	$153.90
Purchase #2	$151.89	11.574%	$169.4697	$169.47	$169.45	$169.50
Purchase #3	$73.59	12.189%	$82.5599	$82.56	$82.55	$82.60
Purchase #4	$146.89	11.472%	$163.7412	$163.74	$163.75	$163.70
Purchase #5	$105.64	7.693%	$113.7669	$113.77	$113.75	$113.80
Purchase #6	$229.43	3.555%	$237.5862	$237.59	$237.60	$237.60
Purchase #7	$109.96	12.138%	$123.3069	$123.31	$123.30	$123.30
7 purchase totals =	$966.38		$1,044.3733	$1,044.38	$1,044.35	$1,044.40