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	$168.38	7.659%	$181.2762	$181.28	$181.30	$181.30
Purchase #2	$240.63	5.777%	$254.5312	$254.53	$254.55	$254.50
Purchase #3	$13.48	13.530%	$15.3038	$15.30	$15.30	$15.30
Purchase #4	$77.50	5.738%	$81.947	$81.95	$81.95	$81.90
Purchase #5	$155.94	6.397%	$165.9155	$165.92	$165.90	$165.90
Purchase #6	$27.44	13.212%	$31.0654	$31.07	$31.05	$31.10
Purchase #7	$208.45	7.240%	$223.5418	$223.54	$223.55	$223.50
7 purchase totals =	$891.82		$953.5809	$953.59	$953.60	$953.50