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	$69.62	4.299%	$72.613	$72.61	$72.60	$72.60
Purchase #2	$155.73	6.255%	$165.4709	$165.47	$165.45	$165.50
Purchase #3	$142.80	8.815%	$155.3878	$155.39	$155.40	$155.40
Purchase #4	$68.69	4.328%	$71.6629	$71.66	$71.65	$71.70
Purchase #5	$238.47	7.712%	$256.8608	$256.86	$256.85	$256.90
Purchase #6	$128.30	7.266%	$137.6223	$137.62	$137.60	$137.60
Purchase #7	$196.95	4.228%	$205.277	$205.28	$205.30	$205.30
7 purchase totals =	$1,000.56		$1,064.8947	$1,064.89	$1,064.85	$1,065.00