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	$196.72	13.669%	$223.6097	$223.61	$223.60	$223.60
Purchase #2	$96.47	13.350%	$109.3487	$109.35	$109.35	$109.30
Purchase #3	$75.58	12.482%	$85.0139	$85.01	$85.00	$85.00
Purchase #4	$76.48	12.839%	$86.2993	$86.30	$86.30	$86.30
Purchase #5	$69.98	8.603%	$76.0004	$76.00	$76.00	$76.00
Purchase #6	$51.74	9.224%	$56.5125	$56.51	$56.50	$56.50
Purchase #7	$200.36	11.776%	$223.9544	$223.95	$223.95	$224.00
7 purchase totals =	$767.33		$860.7389	$860.73	$860.70	$860.70