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	$213.42	7.217%	$228.8225	$228.82	$228.80	$228.80
Purchase #2	$44.62	13.134%	$50.4804	$50.48	$50.50	$50.50
Purchase #3	$68.34	6.692%	$72.9133	$72.91	$72.90	$72.90
Purchase #4	$202.29	9.740%	$221.993	$221.99	$222.00	$222.00
Purchase #5	$168.72	12.776%	$190.2757	$190.28	$190.30	$190.30
Purchase #6	$25.95	10.664%	$28.7173	$28.72	$28.70	$28.70
Purchase #7	$227.50	3.233%	$234.8551	$234.86	$234.85	$234.90
7 purchase totals =	$950.84		$1,028.0573	$1,028.06	$1,028.05	$1,028.10