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	$61.81	4.639%	$64.6774	$64.68	$64.70	$64.70
Purchase #2	$232.44	4.572%	$243.0672	$243.07	$243.05	$243.10
Purchase #3	$243.66	4.686%	$255.0779	$255.08	$255.10	$255.10
Purchase #4	$78.31	13.504%	$88.885	$88.89	$88.90	$88.90
Purchase #5	$125.53	5.269%	$132.1442	$132.14	$132.15	$132.10
Purchase #6	$32.71	7.864%	$35.2823	$35.28	$35.30	$35.30
Purchase #7	$179.47	3.122%	$185.0731	$185.07	$185.05	$185.10
7 purchase totals =	$953.93		$1,004.2071	$1,004.21	$1,004.25	$1,004.30