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	$174.53	6.535%	$185.9355	$185.94	$185.95	$185.90
Purchase #2	$147.44	13.506%	$167.3532	$167.35	$167.35	$167.40
Purchase #3	$55.47	11.725%	$61.9739	$61.97	$61.95	$62.00
Purchase #4	$195.83	13.591%	$222.4453	$222.45	$222.45	$222.40
Purchase #5	$239.76	3.732%	$248.7078	$248.71	$248.70	$248.70
Purchase #6	$232.84	7.562%	$250.4474	$250.45	$250.45	$250.40
Purchase #7	$213.92	4.638%	$223.8416	$223.84	$223.85	$223.80
7 purchase totals =	$1,259.79		$1,360.7047	$1,360.71	$1,360.70	$1,360.60