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	$88.46	7.332%	$94.9459	$94.95	$94.95	$94.90
Purchase #2	$90.31	4.621%	$94.4832	$94.48	$94.50	$94.50
Purchase #3	$31.53	4.172%	$32.8454	$32.85	$32.85	$32.80
Purchase #4	$101.73	13.151%	$115.1085	$115.11	$115.10	$115.10
Purchase #5	$55.26	10.390%	$61.0015	$61.00	$61.00	$61.00
Purchase #6	$164.96	8.574%	$179.1037	$179.10	$179.10	$179.10
Purchase #7	$56.76	7.750%	$61.1589	$61.16	$61.15	$61.20
7 purchase totals =	$589.01		$638.6471	$638.65	$638.65	$638.60