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	$83.25	13.546%	$94.527	$94.53	$94.55	$94.50
Purchase #2	$204.93	4.478%	$214.1068	$214.11	$214.10	$214.10
Purchase #3	$13.35	8.311%	$14.4595	$14.46	$14.45	$14.50
Purchase #4	$131.79	6.347%	$140.1547	$140.15	$140.15	$140.20
Purchase #5	$72.36	8.496%	$78.5077	$78.51	$78.50	$78.50
Purchase #6	$150.28	11.292%	$167.2496	$167.25	$167.25	$167.20
Purchase #7	$196.49	13.743%	$223.4936	$223.49	$223.50	$223.50
7 purchase totals =	$852.45		$932.4989	$932.50	$932.50	$932.50