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	$213.55	4.546%	$223.258	$223.26	$223.25	$223.30
Purchase #2	$58.74	6.430%	$62.517	$62.52	$62.50	$62.50
Purchase #3	$73.97	11.663%	$82.5971	$82.60	$82.60	$82.60
Purchase #4	$67.58	7.541%	$72.6762	$72.68	$72.70	$72.70
Purchase #5	$166.84	4.330%	$174.0642	$174.06	$174.05	$174.10
Purchase #6	$172.77	7.615%	$185.9264	$185.93	$185.95	$185.90
Purchase #7	$238.53	10.334%	$263.1797	$263.18	$263.20	$263.20
7 purchase totals =	$991.98		$1,064.2186	$1,064.23	$1,064.25	$1,064.30