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	$30.40	7.465%	$32.6694	$32.67	$32.65	$32.70
Purchase #2	$49.82	8.336%	$53.973	$53.97	$53.95	$54.00
Purchase #3	$213.92	3.506%	$221.42	$221.42	$221.40	$221.40
Purchase #4	$24.30	3.460%	$25.1408	$25.14	$25.15	$25.10
Purchase #5	$127.78	7.441%	$137.2881	$137.29	$137.30	$137.30
Purchase #6	$76.39	7.542%	$82.1513	$82.15	$82.15	$82.20
Purchase #7	$61.64	5.276%	$64.8921	$64.89	$64.90	$64.90
7 purchase totals =	$584.25		$617.5347	$617.53	$617.50	$617.60