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	$226.77	12.385%	$254.8555	$254.86	$254.85	$254.90
Purchase #2	$106.55	12.764%	$120.15	$120.15	$120.15	$120.20
Purchase #3	$101.61	9.605%	$111.3696	$111.37	$111.35	$111.40
Purchase #4	$239.60	12.161%	$268.7378	$268.74	$268.75	$268.70
Purchase #5	$240.41	12.404%	$270.2305	$270.23	$270.25	$270.20
Purchase #6	$185.98	5.356%	$195.9411	$195.94	$195.95	$195.90
Purchase #7	$167.94	13.405%	$190.4524	$190.45	$190.45	$190.50
7 purchase totals =	$1,268.86		$1,411.7369	$1,411.74	$1,411.75	$1,411.80