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	$89.40	7.327%	$95.9503	$95.95	$95.95	$96.00
Purchase #2	$91.51	9.380%	$100.0936	$100.09	$100.10	$100.10
Purchase #3	$162.31	5.606%	$171.4091	$171.41	$171.40	$171.40
Purchase #4	$222.89	9.161%	$243.309	$243.31	$243.30	$243.30
Purchase #5	$81.38	12.508%	$91.559	$91.56	$91.55	$91.60
Purchase #6	$230.26	3.753%	$238.9017	$238.90	$238.90	$238.90
Purchase #7	$214.73	9.723%	$235.6082	$235.61	$235.60	$235.60
7 purchase totals =	$1,092.48		$1,176.8309	$1,176.83	$1,176.80	$1,176.90