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	$174.95	11.303%	$194.7246	$194.72	$194.70	$194.70
Purchase #2	$20.83	6.854%	$22.2577	$22.26	$22.25	$22.30
Purchase #3	$152.88	4.866%	$160.3191	$160.32	$160.30	$160.30
Purchase #4	$75.56	13.493%	$85.7553	$85.76	$85.75	$85.80
Purchase #5	$168.80	12.250%	$189.478	$189.48	$189.50	$189.50
Purchase #6	$168.69	12.704%	$190.1204	$190.12	$190.10	$190.10
Purchase #7	$183.52	8.140%	$198.4585	$198.46	$198.45	$198.50
7 purchase totals =	$945.23		$1,041.1136	$1,041.12	$1,041.05	$1,041.20