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	$113.64	10.113%	$125.1324	$125.13	$125.15	$125.10
Purchase #2	$141.27	5.733%	$149.369	$149.37	$149.35	$149.40
Purchase #3	$245.40	6.741%	$261.9424	$261.94	$261.95	$261.90
Purchase #4	$242.68	11.238%	$269.9524	$269.95	$269.95	$270.00
Purchase #5	$209.96	6.621%	$223.8615	$223.86	$223.85	$223.90
Purchase #6	$165.61	7.519%	$178.0622	$178.06	$178.05	$178.10
Purchase #7	$173.95	12.711%	$196.0608	$196.06	$196.05	$196.10
7 purchase totals =	$1,292.51		$1,404.3807	$1,404.37	$1,404.35	$1,404.50