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	$198.47	8.454%	$215.2487	$215.25	$215.25	$215.20
Purchase #2	$36.94	3.564%	$38.2565	$38.26	$38.25	$38.30
Purchase #3	$146.93	3.643%	$152.2827	$152.28	$152.30	$152.30
Purchase #4	$85.94	4.360%	$89.687	$89.69	$89.70	$89.70
Purchase #5	$209.51	7.283%	$224.7686	$224.77	$224.75	$224.80
Purchase #6	$61.90	10.672%	$68.506	$68.51	$68.50	$68.50
Purchase #7	$6.35	5.862%	$6.7222	$6.72	$6.70	$6.70
7 purchase totals =	$746.04		$795.4717	$795.48	$795.45	$795.50