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	$124.88	7.262%	$133.9488	$133.95	$133.95	$133.90
Purchase #2	$68.48	13.206%	$77.5235	$77.52	$77.50	$77.50
Purchase #3	$211.44	11.480%	$235.7133	$235.71	$235.70	$235.70
Purchase #4	$196.34	4.290%	$204.763	$204.76	$204.75	$204.80
Purchase #5	$180.31	9.139%	$196.7885	$196.79	$196.80	$196.80
Purchase #6	$158.73	9.654%	$174.0538	$174.05	$174.05	$174.10
Purchase #7	$76.86	12.656%	$86.5874	$86.59	$86.60	$86.60
7 purchase totals =	$1,017.04		$1,109.3783	$1,109.37	$1,109.35	$1,109.40