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	$136.31	8.696%	$148.1635	$148.16	$148.15	$148.20
Purchase #2	$7.78	11.623%	$8.6843	$8.68	$8.70	$8.70
Purchase #3	$186.44	5.502%	$196.6979	$196.70	$196.70	$196.70
Purchase #4	$206.41	8.411%	$223.7711	$223.77	$223.75	$223.80
Purchase #5	$241.44	7.713%	$260.0623	$260.06	$260.05	$260.10
Purchase #6	$83.58	3.830%	$86.7811	$86.78	$86.80	$86.80
Purchase #7	$83.86	10.560%	$92.7156	$92.72	$92.70	$92.70
7 purchase totals =	$945.82		$1,016.8758	$1,016.87	$1,016.85	$1,017.00