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	$132.68	13.109%	$150.073	$150.07	$150.05	$150.10
Purchase #2	$182.97	4.349%	$190.9274	$190.93	$190.95	$190.90
Purchase #3	$165.33	9.685%	$181.3422	$181.34	$181.35	$181.30
Purchase #4	$142.26	9.594%	$155.9084	$155.91	$155.90	$155.90
Purchase #5	$155.48	10.215%	$171.3623	$171.36	$171.35	$171.40
Purchase #6	$109.73	8.745%	$119.3259	$119.33	$119.35	$119.30
Purchase #7	$86.32	3.857%	$89.6494	$89.65	$89.65	$89.60
7 purchase totals =	$974.77		$1,058.5886	$1,058.59	$1,058.60	$1,058.50