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	$164.33	4.632%	$171.9418	$171.94	$171.95	$171.90
Purchase #2	$235.55	4.460%	$246.0555	$246.06	$246.05	$246.10
Purchase #3	$240.43	13.329%	$272.4769	$272.48	$272.50	$272.50
Purchase #4	$104.35	13.418%	$118.3517	$118.35	$118.35	$118.40
Purchase #5	$123.58	3.648%	$128.0882	$128.09	$128.10	$128.10
Purchase #6	$73.38	4.194%	$76.4576	$76.46	$76.45	$76.50
Purchase #7	$32.39	4.198%	$33.7497	$33.75	$33.75	$33.70
7 purchase totals =	$974.01		$1,047.1214	$1,047.13	$1,047.15	$1,047.20