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	$64.42	4.830%	$67.5315	$67.53	$67.55	$67.50
Purchase #2	$9.92	9.133%	$10.826	$10.83	$10.85	$10.80
Purchase #3	$35.57	9.732%	$39.0317	$39.03	$39.05	$39.00
Purchase #4	$222.77	9.413%	$243.7393	$243.74	$243.75	$243.70
Purchase #5	$160.86	4.545%	$168.1711	$168.17	$168.15	$168.20
Purchase #6	$123.68	12.802%	$139.5135	$139.51	$139.50	$139.50
Purchase #7	$73.39	4.461%	$76.6639	$76.66	$76.65	$76.70
7 purchase totals =	$690.61		$745.4770	$745.47	$745.50	$745.40