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	$87.40	11.451%	$97.4082	$97.41	$97.40	$97.40
Purchase #2	$238.31	10.469%	$263.2587	$263.26	$263.25	$263.30
Purchase #3	$94.93	3.510%	$98.262	$98.26	$98.25	$98.30
Purchase #4	$91.99	6.206%	$97.6989	$97.70	$97.70	$97.70
Purchase #5	$141.90	7.470%	$152.4999	$152.50	$152.50	$152.50
Purchase #6	$198.50	12.628%	$223.5666	$223.57	$223.55	$223.60
Purchase #7	$89.73	11.235%	$99.8112	$99.81	$99.80	$99.80
7 purchase totals =	$942.76		$1,032.5055	$1,032.51	$1,032.45	$1,032.60