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	$229.55	10.681%	$254.0682	$254.07	$254.05	$254.10
Purchase #2	$250.57	10.562%	$277.0352	$277.04	$277.05	$277.00
Purchase #3	$152.68	13.672%	$173.5544	$173.55	$173.55	$173.60
Purchase #4	$195.30	5.173%	$205.4029	$205.40	$205.40	$205.40
Purchase #5	$72.72	8.530%	$78.923	$78.92	$78.90	$78.90
Purchase #6	$188.78	4.115%	$196.5483	$196.55	$196.55	$196.50
Purchase #7	$73.94	3.480%	$76.5131	$76.51	$76.50	$76.50
7 purchase totals =	$1,163.54		$1,262.0451	$1,262.04	$1,262.00	$1,262.00