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	$40.90	13.331%	$46.3524	$46.35	$46.35	$46.40
Purchase #2	$96.41	3.538%	$99.821	$99.82	$99.80	$99.80
Purchase #3	$149.88	12.778%	$169.0317	$169.03	$169.05	$169.00
Purchase #4	$142.81	3.577%	$147.9183	$147.92	$147.90	$147.90
Purchase #5	$206.32	3.178%	$212.8768	$212.88	$212.90	$212.90
Purchase #6	$164.70	4.689%	$172.4228	$172.42	$172.40	$172.40
Purchase #7	$224.39	9.164%	$244.9531	$244.95	$244.95	$245.00
7 purchase totals =	$1,025.41		$1,093.3761	$1,093.37	$1,093.35	$1,093.40