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	$69.40	4.686%	$72.6521	$72.65	$72.65	$72.70
Purchase #2	$117.34	13.632%	$133.3358	$133.34	$133.35	$133.30
Purchase #3	$7.62	11.787%	$8.5182	$8.52	$8.50	$8.50
Purchase #4	$19.63	7.486%	$21.0995	$21.10	$21.10	$21.10
Purchase #5	$41.35	9.811%	$45.4068	$45.41	$45.40	$45.40
Purchase #6	$11.69	3.521%	$12.1016	$12.10	$12.10	$12.10
Purchase #7	$185.41	7.785%	$199.8442	$199.84	$199.85	$199.80
7 purchase totals =	$452.44		$492.9582	$492.96	$492.95	$492.90