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	$147.62	7.522%	$158.724	$158.72	$158.70	$158.70
Purchase #2	$59.47	11.621%	$66.381	$66.38	$66.40	$66.40
Purchase #3	$196.51	7.840%	$211.9164	$211.92	$211.90	$211.90
Purchase #4	$31.81	12.551%	$35.8025	$35.80	$35.80	$35.80
Purchase #5	$139.71	12.644%	$157.3749	$157.37	$157.35	$157.40
Purchase #6	$150.92	6.223%	$160.3118	$160.31	$160.30	$160.30
Purchase #7	$236.41	3.119%	$243.7836	$243.78	$243.80	$243.80
7 purchase totals =	$962.45		$1,034.2942	$1,034.28	$1,034.25	$1,034.30