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	$102.64	7.142%	$109.9705	$109.97	$109.95	$110.00
Purchase #2	$233.50	3.494%	$241.6585	$241.66	$241.65	$241.70
Purchase #3	$55.95	10.540%	$61.8471	$61.85	$61.85	$61.80
Purchase #4	$130.64	11.366%	$145.4885	$145.49	$145.50	$145.50
Purchase #5	$77.83	9.411%	$85.1546	$85.15	$85.15	$85.20
Purchase #6	$205.63	7.649%	$221.3586	$221.36	$221.35	$221.40
Purchase #7	$158.99	4.324%	$165.8647	$165.86	$165.85	$165.90
7 purchase totals =	$965.18		$1,031.3425	$1,031.34	$1,031.30	$1,031.50