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	$164.76	4.553%	$172.2615	$172.26	$172.25	$172.30
Purchase #2	$178.59	12.823%	$201.4906	$201.49	$201.50	$201.50
Purchase #3	$178.49	6.643%	$190.3471	$190.35	$190.35	$190.30
Purchase #4	$60.51	4.780%	$63.4024	$63.40	$63.40	$63.40
Purchase #5	$169.56	10.488%	$187.3435	$187.34	$187.35	$187.30
Purchase #6	$79.35	13.391%	$89.9758	$89.98	$90.00	$90.00
Purchase #7	$186.97	5.208%	$196.7074	$196.71	$196.70	$196.70
7 purchase totals =	$1,018.23		$1,101.5283	$1,101.53	$1,101.55	$1,101.50