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	$213.31	4.743%	$223.4273	$223.43	$223.45	$223.40
Purchase #2	$86.52	5.448%	$91.2336	$91.23	$91.25	$91.20
Purchase #3	$119.92	9.601%	$131.4335	$131.43	$131.45	$131.40
Purchase #4	$130.85	6.431%	$139.265	$139.27	$139.25	$139.30
Purchase #5	$177.83	9.704%	$195.0866	$195.09	$195.10	$195.10
Purchase #6	$146.56	6.745%	$156.4455	$156.45	$156.45	$156.40
Purchase #7	$160.33	6.869%	$171.3431	$171.34	$171.35	$171.30
7 purchase totals =	$1,035.32		$1,108.2346	$1,108.24	$1,108.30	$1,108.10