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	$83.85	9.515%	$91.8283	$91.83	$91.85	$91.80
Purchase #2	$69.79	3.700%	$72.3722	$72.37	$72.35	$72.40
Purchase #3	$216.51	4.823%	$226.9523	$226.95	$226.95	$227.00
Purchase #4	$201.43	5.799%	$213.1109	$213.11	$213.10	$213.10
Purchase #5	$40.51	7.411%	$43.5122	$43.51	$43.50	$43.50
Purchase #6	$138.44	12.317%	$155.4917	$155.49	$155.50	$155.50
Purchase #7	$200.43	10.468%	$221.411	$221.41	$221.40	$221.40
7 purchase totals =	$950.96		$1,024.6786	$1,024.67	$1,024.65	$1,024.70