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	$43.37	4.425%	$45.2891	$45.29	$45.30	$45.30
Purchase #2	$85.62	5.700%	$90.5003	$90.50	$90.50	$90.50
Purchase #3	$45.98	4.777%	$48.1765	$48.18	$48.20	$48.20
Purchase #4	$247.30	6.167%	$262.551	$262.55	$262.55	$262.60
Purchase #5	$238.80	9.525%	$261.5457	$261.55	$261.55	$261.50
Purchase #6	$221.38	5.411%	$233.3589	$233.36	$233.35	$233.40
Purchase #7	$40.29	11.391%	$44.8794	$44.88	$44.90	$44.90
7 purchase totals =	$922.74		$986.3009	$986.31	$986.35	$986.40