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	$238.59	11.174%	$265.25	$265.25	$265.25	$265.30
Purchase #2	$103.56	5.482%	$109.2372	$109.24	$109.25	$109.20
Purchase #3	$178.50	4.784%	$187.0394	$187.04	$187.05	$187.00
Purchase #4	$198.47	7.780%	$213.911	$213.91	$213.90	$213.90
Purchase #5	$163.94	5.723%	$173.3223	$173.32	$173.30	$173.30
Purchase #6	$212.50	13.128%	$240.397	$240.40	$240.40	$240.40
Purchase #7	$240.68	13.662%	$273.5617	$273.56	$273.55	$273.60
7 purchase totals =	$1,336.24		$1,462.7186	$1,462.72	$1,462.70	$1,462.70