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	$215.73	13.583%	$245.0326	$245.03	$245.05	$245.00
Purchase #2	$209.50	7.650%	$225.5268	$225.53	$225.55	$225.50
Purchase #3	$33.27	12.668%	$37.4846	$37.48	$37.50	$37.50
Purchase #4	$222.63	9.180%	$243.0674	$243.07	$243.05	$243.10
Purchase #5	$95.55	5.201%	$100.5196	$100.52	$100.50	$100.50
Purchase #6	$246.58	3.240%	$254.5692	$254.57	$254.55	$254.60
Purchase #7	$11.62	9.651%	$12.7414	$12.74	$12.75	$12.70
7 purchase totals =	$1,034.88		$1,118.9416	$1,118.94	$1,118.95	$1,118.90