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	$191.77	9.219%	$209.4493	$209.45	$209.45	$209.40
Purchase #2	$142.34	9.756%	$156.2267	$156.23	$156.25	$156.20
Purchase #3	$129.47	9.651%	$141.9651	$141.97	$141.95	$142.00
Purchase #4	$87.72	9.425%	$95.9876	$95.99	$96.00	$96.00
Purchase #5	$209.32	5.290%	$220.393	$220.39	$220.40	$220.40
Purchase #6	$41.81	9.602%	$45.8246	$45.82	$45.80	$45.80
Purchase #7	$215.53	9.343%	$235.667	$235.67	$235.65	$235.70
7 purchase totals =	$1,017.96		$1,105.5133	$1,105.52	$1,105.50	$1,105.50