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	$141.57	10.866%	$156.953	$156.95	$156.95	$157.00
Purchase #2	$8.54	12.476%	$9.6055	$9.61	$9.60	$9.60
Purchase #3	$151.75	10.123%	$167.1117	$167.11	$167.10	$167.10
Purchase #4	$117.52	8.534%	$127.5492	$127.55	$127.55	$127.50
Purchase #5	$158.32	6.670%	$168.8799	$168.88	$168.90	$168.90
Purchase #6	$186.72	8.740%	$203.0393	$203.04	$203.05	$203.00
Purchase #7	$243.69	6.656%	$259.91	$259.91	$259.90	$259.90
7 purchase totals =	$1,008.11		$1,093.0486	$1,093.05	$1,093.05	$1,093.00