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	$210.92	8.690%	$229.2489	$229.25	$229.25	$229.20
Purchase #2	$164.52	10.779%	$182.2536	$182.25	$182.25	$182.30
Purchase #3	$197.76	13.170%	$223.805	$223.81	$223.80	$223.80
Purchase #4	$73.82	11.414%	$82.2458	$82.25	$82.25	$82.20
Purchase #5	$195.59	6.567%	$208.4344	$208.43	$208.45	$208.40
Purchase #6	$91.66	5.359%	$96.5721	$96.57	$96.55	$96.60
Purchase #7	$52.37	3.204%	$54.0479	$54.05	$54.05	$54.00
7 purchase totals =	$986.64		$1,076.6077	$1,076.61	$1,076.60	$1,076.50