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	$186.80	7.742%	$201.2621	$201.26	$201.25	$201.30
Purchase #2	$74.29	5.716%	$78.5364	$78.54	$78.55	$78.50
Purchase #3	$37.73	10.261%	$41.6015	$41.60	$41.60	$41.60
Purchase #4	$86.61	4.467%	$90.4789	$90.48	$90.50	$90.50
Purchase #5	$160.64	8.780%	$174.7442	$174.74	$174.75	$174.70
Purchase #6	$55.82	7.457%	$59.9825	$59.98	$60.00	$60.00
Purchase #7	$106.57	5.463%	$112.3919	$112.39	$112.40	$112.40
7 purchase totals =	$708.46		$758.9975	$758.99	$759.05	$759.00