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	$182.94	7.525%	$196.7062	$196.71	$196.70	$196.70
Purchase #2	$32.69	7.395%	$35.1074	$35.11	$35.10	$35.10
Purchase #3	$19.55	5.581%	$20.6411	$20.64	$20.65	$20.60
Purchase #4	$37.59	13.824%	$42.7864	$42.79	$42.80	$42.80
Purchase #5	$247.36	5.232%	$260.3019	$260.30	$260.30	$260.30
Purchase #6	$37.78	13.659%	$42.9404	$42.94	$42.95	$42.90
Purchase #7	$152.97	7.857%	$164.9889	$164.99	$165.00	$165.00
7 purchase totals =	$710.88		$763.4723	$763.48	$763.50	$763.40