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	$244.74	3.726%	$253.859	$253.86	$253.85	$253.90
Purchase #2	$78.77	8.736%	$85.6513	$85.65	$85.65	$85.70
Purchase #3	$149.53	13.179%	$169.2366	$169.24	$169.25	$169.20
Purchase #4	$41.95	3.787%	$43.5386	$43.54	$43.55	$43.50
Purchase #5	$152.59	4.293%	$159.1407	$159.14	$159.15	$159.10
Purchase #6	$45.48	13.515%	$51.6266	$51.63	$51.65	$51.60
Purchase #7	$249.51	4.383%	$260.446	$260.45	$260.45	$260.40
7 purchase totals =	$962.57		$1,023.4988	$1,023.51	$1,023.55	$1,023.40