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	$205.98	4.245%	$214.7239	$214.72	$214.70	$214.70
Purchase #2	$107.74	3.866%	$111.9052	$111.91	$111.90	$111.90
Purchase #3	$65.27	10.801%	$72.3198	$72.32	$72.30	$72.30
Purchase #4	$42.58	8.854%	$46.35	$46.35	$46.35	$46.40
Purchase #5	$188.34	8.794%	$204.9026	$204.90	$204.90	$204.90
Purchase #6	$51.91	11.507%	$57.8833	$57.88	$57.90	$57.90
Purchase #7	$246.57	6.808%	$263.3565	$263.36	$263.35	$263.40
7 purchase totals =	$908.39		$971.4413	$971.44	$971.40	$971.50