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	$194.91	10.437%	$215.2528	$215.25	$215.25	$215.30
Purchase #2	$105.57	11.769%	$117.9945	$117.99	$118.00	$118.00
Purchase #3	$159.60	4.111%	$166.1612	$166.16	$166.15	$166.20
Purchase #4	$84.50	13.821%	$96.1787	$96.18	$96.20	$96.20
Purchase #5	$167.81	10.785%	$185.9083	$185.91	$185.90	$185.90
Purchase #6	$194.48	3.127%	$200.5614	$200.56	$200.55	$200.60
Purchase #7	$46.69	13.865%	$53.1636	$53.16	$53.15	$53.20
7 purchase totals =	$953.56		$1,035.2205	$1,035.21	$1,035.20	$1,035.40