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	$104.77	8.731%	$113.9175	$113.92	$113.90	$113.90
Purchase #2	$93.62	11.419%	$104.3105	$104.31	$104.30	$104.30
Purchase #3	$242.55	5.777%	$256.5621	$256.56	$256.55	$256.60
Purchase #4	$162.85	5.512%	$171.8263	$171.83	$171.85	$171.80
Purchase #5	$200.27	5.463%	$211.2108	$211.21	$211.20	$211.20
Purchase #6	$67.50	5.203%	$71.012	$71.01	$71.00	$71.00
Purchase #7	$93.46	6.611%	$99.6386	$99.64	$99.65	$99.60
7 purchase totals =	$965.02		$1,028.4778	$1,028.48	$1,028.45	$1,028.40