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	$205.59	4.146%	$214.1138	$214.11	$214.10	$214.10
Purchase #2	$202.89	11.456%	$226.1331	$226.13	$226.15	$226.10
Purchase #3	$155.45	5.763%	$164.4086	$164.41	$164.40	$164.40
Purchase #4	$69.74	12.387%	$78.3787	$78.38	$78.40	$78.40
Purchase #5	$101.41	4.355%	$105.8264	$105.83	$105.85	$105.80
Purchase #6	$189.53	7.409%	$203.5723	$203.57	$203.55	$203.60
Purchase #7	$28.64	11.253%	$31.8629	$31.86	$31.85	$31.90
7 purchase totals =	$953.25		$1,024.2958	$1,024.29	$1,024.30	$1,024.30