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	$76.82	9.259%	$83.9328	$83.93	$83.95	$83.90
Purchase #2	$24.83	3.592%	$25.7219	$25.72	$25.70	$25.70
Purchase #3	$9.56	6.848%	$10.2147	$10.21	$10.20	$10.20
Purchase #4	$32.42	4.498%	$33.8783	$33.88	$33.90	$33.90
Purchase #5	$91.76	4.684%	$96.058	$96.06	$96.05	$96.10
Purchase #6	$174.41	4.540%	$182.3282	$182.33	$182.35	$182.30
Purchase #7	$30.98	4.720%	$32.4423	$32.44	$32.45	$32.40
7 purchase totals =	$440.78		$464.5762	$464.57	$464.60	$464.50