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	$233.25	5.441%	$245.9411	$245.94	$245.95	$245.90
Purchase #2	$32.81	7.252%	$35.1894	$35.19	$35.20	$35.20
Purchase #3	$243.49	6.304%	$258.8396	$258.84	$258.85	$258.80
Purchase #4	$155.90	5.811%	$164.9593	$164.96	$164.95	$165.00
Purchase #5	$72.60	13.475%	$82.3829	$82.38	$82.40	$82.40
Purchase #6	$91.54	5.537%	$96.6086	$96.61	$96.60	$96.60
Purchase #7	$170.41	5.289%	$179.423	$179.42	$179.40	$179.40
7 purchase totals =	$1,000.00		$1,063.3439	$1,063.34	$1,063.35	$1,063.30